Use of weakly anionic copolymers as dispersing and/or grinding aid agent of an aqueous suspension of mineral materials

ABSTRACT

The invention relates to the use of a slightly anionic and water-soluble copolymer, as a dispersing agent and/or an agent for assisting the grinding of pigments and/or mineral fillers in aqueous suspension giving on the one hand a low Zeta potential to the aqueous suspensions of the said fillers and/or pigments and on the other hand affording an electro-steric stabilisation of the said suspensions.  
     The invention also relates to the said aqueous suspensions of mineral pigments and/or fillers and their uses in the fields of paper, such as the manufacture or coating of paper, and drilling muds used for petroleum prospecting or extraction.  
     The invention also relates to the use of the said dispersing agents and/or agent for assisting the grinding in the field of paints and plastic materials such as thermoplastic or thermosetting resins.

[0001] The present invention relates to the technical sector of mineral fillers, notably for papermaking applications, and their appropriate processing in order to improve either the method of manufacturing the paper sheet, or its properties.

[0002] The invention firstly relates to the use of a slightly anionic and water-soluble copolymer as a dispersing agent and/or an aid to the grinding of mineral pigments and/or fillers in aqueous suspension giving on the one hand a low Zeta potential to the aqueous suspensions of the said fillers and/or pigments and on the other hand affording electro-steric stabilisation of the said suspensions.

[0003] The invention also relates to the said slightly anionic water-soluble agent, dispersing agent and/or aid to the grinding of mineral pigments and/or fillers in aqueous suspension giving on the one hand a low Zeta potential to the aqueous suspensions of the said fillers and/or pigments and on the other hand affording electro-steric stabilisation of the said suspensions.

[0004] The invention also relates to the said aqueous suspensions of mineral pigments and/or fillers and the uses thereof notably in the fields of paper, such as amongst other things the manufacture or coating of the paper, with the obtaining in particular of equal or better properties for the sheet, and notably opacity, gloss or printability, or notably in the field of drilling muds used in prospecting for oil or in oil extraction. The invention also concerns the use of the said slightly anionic water-soluble dispersing agent and/or aid to the grinding in the fields of paints or plastic materials such as thermoplastic or thermosetting resins. Then, the invention relates to the manufactured papers and/or coated papers with the use of the said aqueous suspensions of mineral pigments and/or fillers as well as relates to the drilling muds containing the said aqueous suspensions of mineral pigments and/or fillers.

[0005] This is because, in the manufacture of paper, it is becoming more and more usual to replace some of the cellulose fibres, which are expensive, with mineral fillers and/or pigments, which are less expensive, in order to reduce the cost of the paper whilst improving, for example, its opacity, its whiteness or its properties of printability.

[0006] The mineral fillers and/or pigments such as, for example, natural or synthetic calcium carbonate, dolomites, magnesium hydroxide, kaolin, talc, gypsum, titanium oxide or aluminium hydroxide are normally incorporated in the sheet of paper during its formation on the wire.

[0007] This is achieved by incorporating the mineral filler and/or pigment, either in powder form or in aqueous suspension, in the papermaking pulp in such a way that the pulp is drained onto the wire and the particles of mineral fillers and/or pigments in suspension are retained in the fibrous sheet obtained. Since this retention is not complete, this leads the papermaker to use chemical additives and the manufacturers of fillers to use surface treatment agents for these mineral materials.

[0008] Likewise, when the sheet of paper is treated by coating, the papermaker uses, in his formulation, mineral materials generally put in suspension, either by the papermaker himself or by the manufacturer, using anionic additives such as for example polyacrylates or polyphosphates or others or using cationic additives such as for example cationised polyacrylates or polymethacrylates such as quaternary dimethylaminoethyl methacrylates or melamine-formaldehyde resins, epichlorhydrine resins, dicyandiamide resins or others.

[0009] Thus the skilled man in the art knows agents assisting grinding or water-soluble dispersing agents (FR 2 488 814, FR 2 603 042, EP 0 100 947, EP 0 100 948, EP 0 129 329, EP 0 542 643, EP 0 542 644) consisting of polymers and/or copolymers of the anionic type for producing aqueous suspensions of mineral pigments and/or fillers. However, these have the drawback of requiring the addition of cationic compounds during the process of manufacturing the sheet of paper when they are used in these sheet manufacturing operations, and result in coated papers with an opacity which does not meet the opacity required by the final use when they are used in paper coating operations.

[0010] Moreover, the skilled man in the art knows agents for assisting grinding or water-soluble dispersing agents (ED 0 281 134, EP 0 307 795) consisting of polymers and/or copolymers of the cationic type for producing aqueous suspensions of mineral pigments and/or fillers which present the major risk of incompatibility with any anionic medium present in the papermaking formulations, which may go as far as the caking of the medium, thus blocking production entirely.

[0011] Another solution is known to the skilled man in the art for arriving at aqueous suspensions of mineral pigments and/or fillers which are stable over time and have a high concentration of dry matter at the same time as a fine particle size.

[0012] This solution (WO 91/09067) consists in using amphoteric water-soluble copolymers as a weakly anionic water-soluble dispersing agent and/or aid to the grinding of pigments and/or mineral fillers. However, such copolymers have the drawback of being sensitive to the pH and ionic strength of the medium and also being easily hydrolysable.

[0013] Thus the skilled man in the art is confronted with the problem of obtaining aqueous suspensions of mineral fillers and/or pigments which are refined, stable over time, with a moderate to high concentration of mineral material, which do not present any risk of incompatibility in papermaking formulations, only slightly sensitive to the pH and ionic strength of the media used in papermaking formulations and to the problem of obtaining suspensions making it possible to arrive at sheet properties meeting the criteria of the final user, a problem which none of the solutions available to him completely resolve.

[0014] Bearing in mind the aforementioned drawbacks concerning anionic or cationic aqueous suspensions or aqueous suspensions obtained by means of amphoteric agents, the Applicant unexpectedly found that the presence in the copolymer of at least one monomer of formula (I)

[0015] in which

[0016] m and p represent a number of alkylene oxide units less than or equal to 150,

[0017] n represents a number of ethylene oxide units less than or equal to 150,

[0018] q represents a number at least equal to 1 and such that

5≦(m+n+p)q≦150

[0019] R₁ is hydrogen or the methyl or ethyl radical

[0020] R₂ is hydrogen or the methyl or ethyl radical

[0021] R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as for example acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenlcally unsaturated amides,

[0022] R′ represents a hydrocarbon radical having 1 to 5 carbon atoms

[0023] made possible the development of weakly anionic water-soluble copolymers allowing electro-steric stabilisation thus resulting in the obtaining of aqueous suspensions of mineral pigments and/or fillers resolving the problems set out above, that is to say resulting, notably, in the obtaining of aqueous suspensions of mineral pigments and/or fillers with a moderate to high mineral matter content, stable over time, without sedimentation, only slightly sensitive to the pH and ionic strength of the media used in the papermaking or petroleum formulations, and having a low Zeta potential.

[0024] Thus the prior art essentially describes dispersing agents and/or grinding aid agents which are anionic, cationic or amphoteric or weakly anionic and water-soluble.

[0025] In fact European patent application EP 0 870 784 describes slightly anionic agents, but these agents give aqueous suspensions with a high Zeta potential and do not resolve the problem posed for the final user.

[0026] Thus, according to the invention, the dispersing agent and/or grinding aid agent is distinguished from the prior art in that it is composed of

[0027] a) at least one anionic monomer with a monocarboxylic function

[0028] b) possibly at least one anionic monomer with a dicarboxylic function or with a sulphonic or phosphoric or phosphonic function or a mixture thereof

[0029] c) at least one non-ionic monomer, the non-ionic monomer consisting of at least one monomer of formula (I):

[0030] in which

[0031] m and p represent a number of alkylene oxide units less than or equal to 150,

[0032] n represents a number of ethylene oxide units less than or equal to 150,

[0033] q represents a number at least equal to 1 and such that

5≦(m+n+p)q≦150

[0034] R₁ is hydrogen or the methyl or ethyl radical

[0035] R₂ is hydrogen or the methyl or ethyl radical

[0036] R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as for example acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides,

[0037] R′ represents a hydrocarbon radical having 1 to 5 carbon atoms

[0038] d) possibly a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and

[0039] e) possibly at least one monomer having at least two unsaturated ethylenic chains referred to in the remainder of the application as across-linking monomer

[0040] giving the properties of low Zeta potential and electro-steric stability to the suspensions.

[0041] These aims are achieved by means of the use, as a dispersing agent and/or a grinding aid agent, of a copolymer consisting of:

[0042] a) at least one anionic monomer with an unsaturated ethylenic chain and with a monocarboxylic function

[0043] b) possibly at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof

[0044] c) at least one non-ionic monomer of formula (I) and

[0045] d) possibly a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers with unsaturated ethylenic chains such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof,

[0046] e) possibly at least one cross-linking monomer

[0047] the total of constituents a), b), c), d) and e) being equal to 100%, with moreover the obligatory presence of a monomer of type a) in order to be able to ensure the dispersion of the mineral materials with a high and medium concentration of dry matter and the obligatory presence of a monomer of type c) in combination with the monomer of type a) in order to ensure the electro-steric stabilisation of the aqueous suspensions of mineral materials with a high and medium concentration of dry matter.

[0048] The use according to the invention of a weakly anionic and water-soluble copolymer as a dispersing agent and/or a grinding aid agent for mineral pigments and/or fillers in aqueous suspension is characterised in that the said copolymer consists of:

[0049] a) at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid or diacid hemiesters such as the C₁ to C₄ monoesters of maleic or itaconic acids, or mixtures thereof,

[0050] b) possibly at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof chosen from amongst monomers with an unsaturated ethylenic chain and a dicarboxylic function such as crotonic, isocrotonic, cinnamic, itaconic, maleic or citraconic acid or carboxylic acid anhydrides, such as maleic anhydride, or chosen from amongst monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methylpropane sulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as vinyl phosphoric acid, ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphonic function such as phosphonic vinyl acid, or mixtures thereof

[0051] c) at least one non-ionic monomer with an

[0052]  unsaturated ethylenic chain of formula (I):

[0053] in which

[0054] m and p represent a number of alkylene oxide units less than or equal to 150,

[0055] n represents a number of ethylene oxide units less than or equal to 150,

[0056] q represents a number at least equal to 1 and such that

5≦(m+n+p)q≦150

[0057] R₁ is hydrogen or the methyl or ethyl radical

[0058] R₂ is hydrogen or the methyl or ethyl radical

[0059] R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as for example acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides,

[0060] R′ represents a hydrocarbon radical having 1 to 5 carbon atoms

[0061] d) possibly a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and

[0062] e) possibly at least one cross-linking monomer chosen non-limitatively from the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, and the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose and others,

[0063] the total of constituents a), b), c), d) and e) being equal to 100%

[0064] and in that the said copolymer has a specific viscosity of no more than 10, preferably no more than 5 and highly preferentially no more than 2.

[0065] More particularly the use of the aforementioned copolymer is characterised in that the said copolymer consists, expressed by weight, of:

[0066] a) 2% to 85% and even more particularly 2% to 80% of at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid or the hemiesters of diacids such as the C₁ to C₄ monoesters of maleic or itaconic acids, or mixtures thereof,

[0067] b) from 0% to 80% and even more particularly from 0% to 50% and very particularly from 0% to 20% of at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof chosen from amongst monomers with an unsaturated ethylenic chain and a dicarboxylic function such as crotonic, isocrotonic, cinnamic, itaconic, maleic or citraconic acid or carboxylic acid anhydrides, such as maleic anhydride, or chosen from amongst monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methyl-propane sulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as vinyl phosphoric acid, ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphonic function such as phosphonic vinyl acid, or mixtures thereof

[0068] c) from 20% to 95% of at least one monomer with an unsaturated ethylenic chain of formula (I):

[0069] in which

[0070] m and p represent a number of alkylene oxide units less than or equal to 150,

[0071] n represents a number of ethylene oxide units less than or equal to 150,

[0072] q represents a number at least equal to 1 and such that

5≦(m+n+p)q≦150

[0073] R₁ is hydrogen or the methyl or ethyl radical

[0074] R₂ is hydrogen or the methyl or ethyl radical

[0075] R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as for example acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides,

[0076] R′ represents a hydrocarbon radical having 1 to 5 carbon atoms

[0077] d) from 0% to 50% of a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and

[0078] e) from 0% to 3% of at least one cross-linking monomer chosen non-limitatively from the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, or the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others,

[0079] the total of constituents a), b), c), d) and e) being equal to 100%

[0080] and in that the said copolymer has a specific viscosity of no more than 10, preferably no more than 5 and highly preferentially no more than 2.

[0081] Even more preferentially, the use of the copolymer is characterised in that

[0082] a) the anionic monomer with unsaturated ethylenic chains and monocarboxylic function is preferably chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid,

[0083] b) the anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof is preferably chosen from amongst the monomers with an unsaturated ethylenic chain and a dicarboxylic function such as diacids including itaconic or maleic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methyl-propanesulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or mixtures thereof

[0084] c) the non-ionic monomer with an unsaturated ethylenic chain of formula (I) is such that

[0085] R₁ represents hydrogen or the methyl or ethyl radical

[0086] R₂ represents hydrogen or the methyl or ethyl radical

[0087] R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters as well as unsaturated urethanes such as for example acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane, allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides,

[0088] R′ represents a hydrocarbon radical having 1 to 5 carbon atoms

[0089] d) the monomer of the acrylamide or methacrylamide type or derivatives thereof is chosen from amongst acrylamide or methacrylamide, and the non water-soluble monomer is chosen from amongst ethyl acrylate or styrene

[0090] e) the cross-linking agent is chosen from amongst the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, the allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others.

[0091] The copolymer used according to the invention is obtained by known methods of radical copolymerisation in solution, in direct or reverse emulsion, in suspension or precipitation in suitable solvents, in the presence of catalytic systems and known transfer agents.

[0092] This copolymer obtained in acid form and possibly distilled can also be partially or completely neutralised by one or more neutralisation agents having a monovalent neutralising function or a polyvalent neutralising function such as for example, for the monovalent function, those chosen from the group consisting of alkali cations, in particular sodium, potassium, lithium, ammonium or the aliphatic and/or cyclic primary, secondary or tertiary amines such as for example stearylamine, the ethanolamines (mono-, di, triethanolamine), mono and diethylamine, cyclohexylamine, methylcyclohexylamine or, for the polyvalent function, those chosen from the group consisting of alkaline-earth divalent cations, in particular magnesium and calcium, or zinc, also consisting of trivalent cations, in particular aluminium, or certain cations with a higher valency.

[0093] Each neutralisation agent then acts according to the degrees of neutralisation peculiar to each valency function.

[0094] According to another variant, the copolymer resulting from the copolymerisation reaction can, possibly before or after the complete or partial neutralisation reaction, be treated and separated into several phases, according to static or dynamic methods known to experts, by means of one or more polar solvents belonging notably to the group consisting of water, methanol, ethanol, propanol, isopropanol, the butanols, acetone, tetrahydrofuran or mixtures thereof.

[0095] One of the phases then corresponds to the copolymer used according to the invention as a dispersing agent and/or a grinding aid agent for mineral materials in aqueous suspension.

[0096] The specific viscosity of the copolymer is symbolised by the letter η and is determined as follows:

[0097] A solution of polymerisate is taken so as to obtain a solution corresponding to 2.5 g of dry polymer neutralised with soda and to 50 ml of a solution of bipermuted water. Then, with a capillary viscometer with a Baume constant of 0.000105 placed in a bath thermostatically controlled at 25° C., a measurement is made of the run-out time for a given volume of the aforementioned solution containing the copolymer, and the run-out time for the same volume of the solution of bipermuted water without the said copolymer. It is then possible to define the specific viscosity η by means of the following equation: $\eta = \frac{\begin{matrix} \left( {{run}\text{-}{out}\quad {time}\quad {of}} \right. \\ \left. {{the}\quad {polymer}\quad {solution}} \right) \end{matrix} - \begin{matrix} \left( {{run}\text{-}{out}\quad {time}\quad {of}\quad {the}} \right. \\ \left. {{permuted}\quad {water}\quad {solution}} \right) \end{matrix}}{\left( {{run}\text{-}{out}\quad {time}\quad {of}\quad {the}\quad {permuted}\quad {water}\quad {solution}} \right)}$

[0098] The capillary tube is generally chosen so that the run-out time of the permuted water solution with no copolymer is approximately 60 to 100 seconds, thus giving specific viscosity measurements with very good precision.

[0099] The invention also relates to the said water-soluble, weakly anionic agent, dispersing agent and/or grinding aid agent for pigments and/or mineral fillers in aqueous suspension giving on the one hand a low Zeta potential to the aqueous suspensions of the said fillers and/or pigments and on the other hand affording an electro-steric stabilisation of the said suspensions. This agent is characterised in that it is the previously described copolymer.

[0100] The aqueous suspensions of fillers and/or pigments according to the invention are characterised in that they contain the said agent and more particularly in that they contain from 0.05% to 5% by dry weight of the said agent with respect to the total dry weight of the fillers and/or pigments, and even more particularly 0.3% to 1.0% by dry weight of the said agent with respect to the total dry weight of the fillers and/or pigments.

[0101] They are also characterised in that the filler and/or pigment is chosen from amongst natural calcium carbonate such as notably calcite, chalk or marble, synthetic calcium carbonate named precipitated calcium carbonate, dolomites, magnesium hydroxide, kaolin, talc, gypsum, titanium oxide, or aluminium hydroxide or any other filler and/or pigment normally used in the papermaking or petroleum field.

[0102] Finally, they are characterised in that they are only slightly sensitive to the pH and ionic strength of the media and in that they have a low Zeta potential, that is to say a Zeta potential of between 0 and −30 mV and preferentially between 0 and −20 mV.

[0103] The papers manufactured and/or coated according to the invention are characterised in that they contain the said aqueous suspensions of fillers and/or pigments according to the invention.

[0104] The drilling muds according to the invention are characterised in that they contain the said aqueous suspensions of fillers and/or pigments according to the invention.

[0105] In practice, the dispersing operation, also referred to as the operation of dispersing the mineral filler to be dispersed, can be effected in two different ways.

[0106] One of the ways consists in effecting, under agitation, the preparation of a suspension of mineral filler and/or pigment by introducing all or part of the dispersing agent according to the invention into the aqueous phase, and then the mineral material, so as to obtain an aqueous suspension with a moderate to high mineral material content, stable over time, without sedimentation, only slightly sensitive to the pH and ionic strength of the media used in the papermaking formulations, and having a low Zeta potential, that is to say a Zeta potential of between 0 and −30 mV and preferentially between 0 and −20 mV.

[0107] Another way consists in preparing the suspension of mineral filler and/or pigment by introducing into the mineral filler and/or pigment cake all the quantity of dispersing agent to be tested so as to obtain an aqueous suspension with a moderate to high mineral material content, stable over time, without sedimentation, only slightly sensitive to the pH and ionic strength of the media used in the papermaking formulations, and having a low Zeta potential, that is to say a Zeta potential of between 0 and −30 mV and preferentially between 0 and −20 mV.

[0108] This dispersing operation can follow on from the grinding operation described below or can be implemented completely independently.

[0109] Thus, in practice, the operation of grinding the mineral material to be refined consists in grinding the mineral substance with a grinding substance of very fine particles in an aqueous medium containing the grinding aid agent.

[0110] To the aqueous suspension of the mineral substance to be ground, the grinding substance with a particle size advantageously between 0.20 and 4 millimetres is added. The grinding substance is generally in the form of particles of materials which are as diverse as silicon oxide, aluminium oxide, zirconium oxide or mixtures thereof, and synthetic resins with high hardness, steels, or others. An example of the composition of such grinding substances is given by the patent FR 2 303 681, which describes the grinding element formed by 30% to 70% by weight zirconium oxide, 0.1% to 5% aluminium oxide and 5% to 20% silicon oxide.

[0111] The grinding substance is preferably added to the suspension in a quantity such that the ratio by weight between this grinding material and the mineral substance to be ground is at least 2/1, this ratio preferably being between the limits 3/1 and 5/1.

[0112] The mixture of the suspension and grinding substance is then subjected to the mechanical action of stirring, such as the one which occurs in a conventional grinder with microelements.

[0113] The time required for achieving the required fineness of the mineral substance after grinding varies according to the nature and quantity of the mineral substances to be ground, and according to the stirring mode used and the temperature of the medium during the grinding operation.

[0114] The aqueous suspensions thus obtained can be used in the field of paper in mass filling or in coating with a low Zeta potential.

[0115] During the manufacture of the sheet of paper, that is to say during their use as a mass filler, these suspensions can be used with the coating broke.

[0116] They can also be used in the field of drilling muds such as for example soft bentonitic muds, saturated salt muds and sea-water muds.

[0117] The scope and interest of the invention will be perceived more clearly by means of the following examples, which are not limitative.

EXAMPLE 1

[0118] This example relates to the preparation of a calcium carbonate suspension by simple dispersion and the revealing of the properties afforded by the presence of at least one monomer of formula (I) in the non-ionic monomer.

[0119] To this end, for each of the following tests, carried out using a marble filtration cake in which 73% of the particles have a diameter less than 1 micrometre determined by measurement using the Sedigraph™ 5100 from Micromeritics, the aqueous suspension of marble is prepared by the introduction, into the cake, of the necessary quantity by dry weight of dispersion agent to be tested with respect to the dry weight of the said cake to be put in suspension in order to obtain an aqueous suspension of calcium carbonate with a dry matter concentration of 61%.

[0120] After 20 minutes stirring, a sample of the suspension of calcium carbonate obtained is recovered in a flask and the Brookfield™ viscosity is measured by means of a Brookfield™ type RVT viscometer, at a temperature of 25° C. and a speed of rotation of 10 and 100 revolutions per minute with the appropriate spindle.

[0121] After a time of 8 days in the flask, the Brookfield™ viscosity of the suspension is measured by introducing, into the unstirred flask, the appropriate spindle of the Brookfield™ type RVT viscometer, at a temperature of 25° C. and a speed of rotation of 10 revolutions and 100 revolutions per minute (BS viscosity Brookfield™ viscosity before stirring).

[0122] The same Brookfield™ viscosity measurements are also made once the flask has been stirred and constitute the results of Brookfield™ viscosity after stirring (AS viscosity).

[0123] For measuring the Zeta potential, a sample of the suspension of calcium carbonate obtained is also recovered, after the 20 minutes of stirring, and a few drops of this is dispersed in a sufficient quantity of serum obtained by mechanical filtration of the said suspension in order to obtain a colloidal suspension which is scarcely cloudy.

[0124] This suspension is introduced into the measuring cell of the Zetamaster S Zetameter from Malvern, which directly displays the value of the Zeta potential in mV.

[0125] These different measurements were carried out for the following tests.

[0126] Test N^(o) 1:

[0127] This test, illustrating the prior art, used 0.7% by dry weight of a sodium polyacrylate with a specific viscosity of 4.80.

[0128] Test N^(o) 2:

[0129] This test, illustrating the prior art, used 0.7% by dry weight of an acrylic acid-maleic anhydride copolymer completely neutralised with soda and with a specific viscosity of 1.38.

[0130] Test N^(o) 3:

[0131] This test, illustrating a field outside the invention, used 0.7% by dry weight of a homopolymer, with a specific viscosity of 0.91 and whose single monomer is a monomer of formula (I) in which:

[0132] R₁ represents hydrogen

[0133] R₂ represents hydrogen

[0134] R represents the methacrylate group

[0135] R′ represents the methyl radical

[0136]  with (m+n+p)q=45.

[0137] Test N^(o) 4:

[0138] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.28 and consisting of:

[0139] a) 8.0% by weight acrylic acid as an anionic monomer with a monocarboxylic function

[0140] b) 5.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0141] c) 82.0% by weight of a monomer of formula (I) in which:

[0142] R₁ represents hydrogen

[0143] R₂ represents hydrogen

[0144] R represents the methacrylurethane group

[0145] R′ represents the methyl radical

[0146] d) 4.5% by weight ethyl acrylate

[0147]  with (m+n+p)q=113.

[0148] Test N^(o) 5:

[0149] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.78 and consisting of:

[0150] a) 8.0% by weight acrylic acid as an anionic monomer with a monocarboxylic function

[0151] b) 5.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0152] c) 75.0% by weight of a monomer of formula (I) in which

[0153] R₁ represents hydrogen

[0154] R₂ represents hydrogen

[0155] R represents the methacrylurethane group

[0156] R′ represents the methyl radical

[0157] d) 11.5% by weight ethyl acrylate

[0158]  with (m+n+p)q=40.

[0159] Test N^(o) 6:

[0160] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.51 and consisting of:

[0161] a) 8.0% by weight acrylic acid as an anionic monomer with a monocarboxylic function

[0162] b) 5.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0163] c) 71.0% by weight of a monomer of formula (I) in which

[0164] R₁ represents hydrogen

[0165] R₂ represents hydrogen

[0166] R represents the methacrylurethane group

[0167] R′ represents the methyl radical

[0168] d) 15.5% by weight ethyl acrylate

[0169]  with (m+n+p)q=25.

[0170] Test N^(o) 7:

[0171] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.51 and consisting of:

[0172] a) 8.0% by weight acrylic acid as an anionic monomer with a monocarboxylic function

[0173] b) 5.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0174] c) 67.0% by weight of a monomer of formula (I) in which

[0175] R₁ represents hydrogen

[0176] R₂ represents hydrogen

[0177] R represents the methacrylurethane group

[0178] R′ represents the methyl radical

[0179] d) 19.5% by weight ethyl acrylate

[0180]  with (m+n+p)q=17.

[0181] Test N^(o) 8:

[0182] This test, illustrating the invention, used 0.6% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.56 and consisting of:

[0183] a) 2.0% by weight methacrylic acid as an anionic monomer with a monocarboxylic function

[0184] b) 13.0% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0185] c) 85.0% by weight of a monomer of formula (I) in which

[0186] R₁ represents hydrogen

[0187] R₂ represents hydrogen

[0188] R represents the methacrylate group

[0189] R′ represents the methyl radical

[0190]  with (m+n+p)q=113.

[0191] Test N^(o) 9:

[0192] This test, illustrating the invention, used 0.6% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.97 and consisting of:

[0193] a) 3.2% by weight methacrylic acid as an anionic monomer with a monocarboxylic function

[0194] b) 13.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0195] c) 83.3% by weight of a monomer of formula (I) in which

[0196] R₁ represents hydrogen

[0197] R₂ represents hydrogen

[0198] R represents the methacrylate group

[0199] R′ represents the methyl radical

[0200]  with (m+n+p)q=45.

[0201] Test N^(o) 10:

[0202] This test, illustrating the invention, used 0.6% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.96 and consisting of:

[0203] a) 8.5% by weight methacrylic acid as an anionic monomer with a monocarboxylic function

[0204] b) 13.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0205] c) 78.0% by weight of a monomer of formula (I) in which

[0206] R₁ represents hydrogen

[0207] R₂ represents hydrogen

[0208] R represents the methacrylate group

[0209] R′ represents the methyl radical

[0210]  with (m+n+p)q=17.

[0211] Test N^(o) 11:

[0212] This test, illustrating the invention, used 0.6% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.07 and consisting of:

[0213] a) 17.0% by weight methacrylic acid as an anionic monomer with a monocarboxylic function

[0214] b) 83.0% by weight of a monomer of formula (I) in which

[0215] R₁ represents hydrogen

[0216] R₂ represents hydrogen

[0217] R represents the methacrylate group

[0218] R′ represents the methyl radical

[0219]  with (m+n+p)q=45.

[0220] Test N^(o) 12:

[0221] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.04 and consisting of:

[0222] a) 3.2% by weight methacrylic acid and 13.0% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0223] b) 8.0% by weight acrylamido methyl propanesulphonic acid as an anionic monomer with a sulphonic function

[0224] c) 75.8% by weight of a monomer of formula (I) in which

[0225] R₁ represents hydrogen

[0226] R₂ represents hydrogen

[0227] R represents the methacrylate group

[0228] R′ represents the methyl radical

[0229]  with (m+n+p)q=45.

[0230] Test N^(o) 13:

[0231] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.47 and consisting of:

[0232] a) 3.3% by weigh methacrylic acid and 13.0% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0233] b) 5.0% by weight itaconic acid as an anionic monomer with a dicarboxylic function

[0234] c) 78.7% by weight of a monomer of formula (I) in which

[0235] R₁ represents hydrogen

[0236] R₂ represents hydrogen

[0237] R represents the methacrylate group

[0238] R′ represents the methyl radical

[0239]  with (m+n+p)q=45.

[0240] Test N^(o) 14:

[0241] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.38 and consisting of:

[0242] a) 0.8% by weight methacrylic acid and 79.3% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0243] b) 19.9% by weight of a monomer of formula (I) in which

[0244] R₁ represents hydrogen

[0245] R₂ represents hydrogen

[0246] R represents the methacrylate group

[0247] R′ represents the methyl radical

[0248]  with (m+n+p)q=45.

[0249] Test N^(o) 15:

[0250] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.38 and consisting of:

[0251] a) 0.4% by weight methacrylic acid and 79.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0252] b) 20.0% by weight of a monomer of formula (I) in which

[0253] R₁ represents hydrogen

[0254] R₂ represents hydrogen

[0255] R represents the methacrylate group

[0256] R′ represents the methyl radical

[0257]  with (m+n+p)q=113.

[0258] Test N^(o) 16:

[0259] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.28 and consisting of:

[0260] a) 35.0% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0261] b) 20.0% by weight of a monomer of formula (I) in which

[0262] R₁ represents hydrogen

[0263] R₂ represents hydrogen

[0264] R represents the methacrylurethane group

[0265] R′ represents the methyl radical

[0266] c) 45.0% by weight acrylamide

[0267]  with (m+n+p)q=17.

[0268] Test N^(o) 17:

[0269] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.03 and consisting of:

[0270] a) 35.0% by weight acrylic acid as an anionic monomer with a monocarboxylic function

[0271] b) 20.0% by weight of a monomer of formula (I) in which

[0272] R₁ represents hydrogen

[0273] R₂ represents hydrogen

[0274] R represents the methacrylate group

[0275] R′ represents the methyl radical

[0276] c) 45.0% by weight acrylamide

[0277]  with (m+n+p)q=45.

[0278] Test N^(o) 18:

[0279] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.65 and consisting of:

[0280] a) 15.0% by weight methacrylic acid and 12.0% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0281] b) 73.0% by weight of a monomer of formula (I) in which

[0282] R₁ represents hydrogen

[0283] R₂ represents hydrogen

[0284] R represents the methacrylate group

[0285] R′ represents the methyl radical

[0286]  with (m+n+p)q=8.

[0287] Test N^(o) 19:

[0288] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.38 and consisting of:

[0289] a) 3.4% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0290] b) 82.1% by weight of a monomer of formula (I) in which

[0291] R₁ represents hydrogen

[0292] R₂ represents hydrogen

[0293] R represents the methacrylate group

[0294] R′ represents the methyl radical

[0295] c) 1.0% by weight EDMA as a cross-linking monomer

[0296]  with (m+n+p)q=45.

[0297] Test N^(o) 20:

[0298] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.16 and consisting of:

[0299] a) 3.9% by weight methacrylic acid and 1.1% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0300] b) 95.0% by weight of a monomer of formula (I) in which

[0301] R₁ represents hydrogen

[0302] R₂ represents hydrogen

[0303] R represents the methacrylate group

[0304] R′ represents the methyl radical

[0305]  with (m+n+p)q=45.

[0306] Test N^(o) 21:

[0307] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.07 and consisting of:

[0308] a) 0.8% by weight methacrylic acid and 79.2% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0309] b) 20.0% by weight of a monomer of formula (I) in which

[0310] R₁ represents hydrogen

[0311] R₂ represents hydrogen

[0312] R represents the methacrylate group

[0313] R′ represents the methyl radical

[0314]  with (m+n+p)q=45.

[0315] Test N^(o) 22:

[0316] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.28 and consisting of:

[0317] a) 1.7% by weight methacrylic acid and 13.2% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0318] b) 85.6% by weight of a monomer of formula (I) in which

[0319] R₁ represents hydrogen

[0320] R₂ represents hydrogen

[0321] R represents the methacrylate group

[0322] R′ represents the propyl radical

[0323]  with (m+n+p)q=64.

[0324] Test N^(o) 22 bis:

[0325] This test, illustrating the invention, used 0.7% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.68 and consisting of:

[0326] a) 45% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0327] b) 35% by weight acrylamido methyl propanesulphonic acid as an anionic monomer with a sulphonic function

[0328] c) 20% by weight of 2 monomer of formula (I) in which

[0329] R₁ represents hydrogen

[0330] R₂ represents hydrogen

[0331] R represents the methacrylate group

[0332] R′ represents the methyl radical

[0333]  with (m+n+p)q=17.

[0334] All the experimental results are set out in the following Tables 1a to 1d. TABLE 1a BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST SPECIFIC 0 100 0 100 0 100 POTENTIAL N° CONSTITUENT MONOMERS VISCOSITY rev/min rev/min rev/min rev/min rev/min rev/min (mV) Prior art  1 100% AA 4.80 1000 280 6000 1500  1000 300 −50.6 Prior art  2 70% AA 30% Maleic anhydride 1.38  180 110 2000 500  400 150 −50.7 Field  3 100% methoxy PEGM 2000 0.91 2400 1600  Excessively high non-measurable viscosity outside invention Invention  4 8.0% AA 1.28 4680 830 2000 600 1000 440 −20.2 5.5% EGMP 82.0% methoxy PEG MU 5000 4.5% EA Invention  5 8.0% AA 0.78 3960 1044  7600 960 4000 840 −16.8 5.5% EGMP 75.0% methoxy PEG MU 1800 11.5% EA Invention  6 8.0% AA 5.5% EGMP 71.0% methoxy PEG MU 1100 0.51 1860 455 3200 1140  1450 520 −20.7 15.5% EA

[0335] TABLE 1b BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST SPECIFIC 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS VISCOSITY rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention  7 8.0% AA 0.51 7600 968 9300 1500  7300 1540  −23.3 5.5% EGMP 67.0% methoxy PEG MU 750 19.5% EA Invention  8 2.0% MAA 1.56 1800 500 3200 800 1300 450 −7.3 13.0% EGMP 85.0% methoxy PEGM 5000 Invention  9 3.2% MAA 0.97  750 330 3000 500  700 240 −12.6 13.5% EGMP 83.3% methoxy PEGM 2000 Invention 10 8.5% MAA 0.96 1200 280 5600 920 1700 370 −25.2 13.5% EGMP 78.0% methoxy PEGM 750 Invention 11 17.0% MAA 1.07 1700 550 1360 750 1980 650 −16.5 83.0% methoxy PEGM 2000 Invention 12 3.2% MAA 1.04 2800 790 3000 900 2100 530 −18.7 13.0% AA 8.0% AMPS 75.8% methoxy PEGM 2000

[0336] TABLE 1c BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST SPECIFIC 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS VISCOSITY rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 13 3.3% MMA 1.47 1100  330 6000 1000 1900 570 −10.9 13.0% AA 5.0% ITCA 78.7% methoxy PEGM 2000 Invention 14 0.8% MMA 1.38 7000 1000 8000 1100 6000 810 −27.5 79.3% AA 19.9% methoxy PEGM 2000 Invention 15 0.4% MMA 1.38 6800  900 8000 1080 5600 800 −24.5 79.6% AA 20.0% methoxy PEGM 5000 Invention 16 35.0% AA 1.28 7400 1020 9100 1340 7240 1040  −29.8 20.0% methoxy PEG MU 750 45.0% Acrylamide Invention 17 35.0% AA 1.03 8000 1060 11800  1630 7500 1080  −25.7 20.0% methoxy PEGM 2000 45.0% Acrylamide Invention 18 15.0% MMA 1.65 2200  650 7000 1150 1600 380 −29.8 12.0% AA 73.0% methoxy PEGM 350

[0337] TABLE 1d BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST SPECIFIC 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS VISCOSITY rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 19 3.4% MMA 1.38 3400  650 12000  2000 2100  520 −12.5 13.5% AA 82.1% methoxy PEGM 2000 1.0% EDMA Invention 20 3.9% MMA 1.16 9000 3600 11000  4250 5150 2000 −12.5 1.1% AA 95.0% methoxy PEGM 2000 Invention 21 0.8% MMA 1.07 9400 1080 9000 1250 8050 1150 −20.3 79.2% AA 20.0% methoxy PEGM 2000 Invention 22 1.7% MMA 1.28 11200  1440 12000  2100 9000 1200 −16.5 13.2% AA 85.6% propoxy PEGM 2800 Invention 22 45% AA 0.68 3450  685 3880 1156 3100  653 −28 bis 35% AMPS 20% methoxy PEGM 750

[0338] A reading of Tables 1a to 1d shows that the use of copolymer according to the invention containing, as a non-ionic monomer, at least one monomer of formula (I) results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential.

EXAMPLE 2

[0339] The purpose of this example is to illustrate different levels of use of dispersing agent according to the invention.

[0340] To this end, with the same operating method and the same equipment as in example 1, different levels of copolymer according to the invention are tested.

[0341] Test N^(o) 23:

[0342] This test, illustrating the invention, used 0.4% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.98 and consisting of:

[0343] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0344] b) 83.0% by weight of a monomer of formula (I) in which

[0345] R₁ represents hydrogen

[0346] R₂ represents hydrogen

[0347] R represents the methacrylate group

[0348] R′ represents the methyl radical

[0349]  with (m+n+p)q=45.

[0350] Test N^(o) 24:

[0351] This test, illustrating the invention, used 0.6% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.17 and consisting of:

[0352] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0353] b) 83.0% by weight of a monomer of formula (I) in which

[0354] R₁ represents hydrogen

[0355] R₂ represents hydrogen

[0356] R represents the methacrylate group

[0357] R′ represents the methyl radical

[0358]  with (m+n+p)q=11.

[0359] Test N^(o) 25:

[0360] This test, illustrating the invention, used 1.0% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.86 and consisting of:

[0361] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0362] b) 83.0% by weight of a monomer of formula (I) in which

[0363] R₁ represents hydrogen

[0364] R₂ represents hydrogen

[0365] R represents the methacrylate group

[0366] R′ represents the methyl radical

[0367]  with (m+n+p)q=17.

[0368] All the experimental results are set out in Table 2 below. TABLE 2 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER QUANTITY INITIAL STIRRING STIRRING ZETA TEST OF AGENT 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS (% dry/dry) rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 23 3.5% MMA 0.4 2000 480 1800 660 1890 540 −20.8 13.5% AA 83.0% methoxy PEGM 2000 Invention 24 3.5% MMA 0.6 2600 540 3000 750 2500 510 −24.2 13.5% AA 83.0% methoxy PEGM 500 Invention 25 3.5% MMA 1.0 8000 1300  9000 1600  8500 1500  −25.9 13.5% AA 83.0% methoxy PEGM 750

[0369] A reading of Table 2 shows that the aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential, contain 0.05% to 5% by dry weight of the agent according to the invention compared with the total dry weight of the fillers and/or pigments, and even more particularly 0.3% to 1.0% by dry weight of the said agent with respect to the total dry weight of the fillers and/or pigments.

EXAMPLE 3

[0370] The purpose of this example is to illustrate the different values of the product (m+n+p)q of the monomer with an unsaturated ethylenic non-ionic chain of formula (I) of the dispersing agent according to the invention.

[0371] For this purpose, with the same operating mode and the same equipment as in example 1, different copolymers according to the invention are tested.

[0372] Test N^(o) 26:

[0373] This test, illustrating the invention, used 0.4% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.19 and consisting of:

[0374] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0375] b) 83.0% by weight of a monomer of formula (I) in which

[0376] R₁ represents hydrogen

[0377] R₂ represents hydrogen

[0378] R represents the methacrylate group

[0379] R′ represents the methyl radical

[0380]  with (m+n+p)q=17.

[0381] Test N^(o) 27:

[0382] This test, illustrating the invention, used 0.8% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 0.81 and consisting of:

[0383] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0384] b) 83.0% by weight of a monomer of formula (I) in which

[0385] R₁ represents hydrogen

[0386] R₂ represents hydrogen

[0387] R represents the methacrylate group

[0388] R′ represents the methyl radical

[0389]  with (m+n+p)q=25.

[0390] Test N^(o) 28:

[0391] This test, illustrating the invention, used 0.4% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 1.05 and consisting of:

[0392] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0393] b) 83.0% by weight of a monomer of formula (T) in which

[0394] R₁ represents hydrogen

[0395] R₂ represents hydrogen

[0396] R represents the methacrylate group

[0397] R′ represents the methyl radical

[0398]  with (m+n+p)q=45.

[0399] Test N^(o) 29:

[0400] This test, illustrating the invention, used 0.4% by dry weight of a polymer fully neutralised with soda, with a specific viscosity of 2.57 and consisting of:

[0401] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0402] b) 83.0% by weight of a monomer of formula (I) in which

[0403] R₁ represents hydrogen

[0404] R₂ represents hydrogen

[0405] R represents the methacrylate group

[0406] R′ represents the methyl radical

[0407]  with (m+n+p)q=113.

[0408] All the experimental results are set out in Table 3 below. TABLE 3 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS (m + n + p)q rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 26 3.5% MMA 17 4000 820 3200  980 4500 930 −23.9 13.5% AA 83.0% methoxy PEGM 750 Invention 27 3.5% MMA 25 3200 810 4000 1000 3500 940 −22.1 13.5% AA 83.0% methoxy PEGM 1100 Invention 28 3.5% MMA 45 2000 470 3000  850 2230 590 −18.6 13.5% AA 83.0% methoxy PEGM 2000 Invention 29 3.5% MMA 113 4600 820 9000 1600 5000 1200  −6.7 13.5% AA 83.0% methoxy PEGM 5000

[0409] A reading of Table 3 shows that the use of a copolymer according to the invention containing, as a non-ionic monomer, at least one monomer of formula (I) with 5≦(m+n+p)q≦150 results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential.

EXAMPLE 4

[0410] The purpose of this example is to illustrate different molecular weights of the dispersing agent according to the invention.

[0411] For this purpose, with the same operating mode and the same equipment as in example 1, tests were carried out on different copolymers which all had a different specific viscosity for the same composition by weight of monomer and the same form of neutralisation.

[0412] For tests 30 to 35, these were copolymers fully neutralised with soda and consisting of

[0413] a) 3.2% by weight methacrylic acid as an anionic monomer with a monocarboxylic function

[0414] b) 13.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0415] c) 83.3% by weight of a monomer of formula (I) in which:

[0416] R₁ represents hydrogen

[0417] R₂ represents hydrogen

[0418] R represents the methacrylate group

[0419] R′ represents the methyl radical

[0420]  with (m+n+p)q=45.

[0421]  and having the following specific viscosities:

[0422] Test N^(o) 30:

[0423] The polymer used in this test, at 0.6% by dry weight with respect to the dry weight of marble, has a specific viscosity of 0.97 and illustrates the invention.

[0424] Test N^(o) 31:

[0425] The polymer used in this test, at 0.6% by dry weight with respect to the dry weight of marble, has a specific viscosity of 1.57 and illustrates the invention.

[0426] Test N^(o) 32:

[0427] The polymer used in this test, at 1.0% by dry weight with respect to the dry weight of marble, has a specific viscosity of 1.75 and illustrates the invention.

[0428] Test N^(o) 33:

[0429] The polymer used in this test, at 0.8% by dry weight with respect to the dry weight of marble, has a specific viscosity of 3.72 and illustrates the invention.

[0430] Test N^(o) 34:

[0431] The polymer used in this test, at 1.0% by dry weight with respect to the dry weight of marble, has a specific viscosity of 3.74 and illustrates the invention.

[0432] Test N^(o) 35:

[0433] The polymer used in this test, at 1.0% by dry weight with respect to the dry weight of marble, has a specific viscosity of 5.08 and illustrates the invention.

[0434] For tests 36 to 39, these are copolymers fully neutralised with soda and consisting of

[0435] a) 8.0% by weight acrylic acid as an anionic monomer with a monocarboxylic function

[0436] b) 5.5% by weight ethylene glycol methacrylate phosphate as an anionic monomer with a phosphoric function

[0437] c) 82.0% by weight of a monomer of formula (I) in which:

[0438] R₁ represents hydrogen

[0439] R₂ represents hydrogen

[0440] R represents the methacrylurethane group

[0441] R′ represents the methyl radical

[0442] d) 4.5% by weight ethyl acrylate

[0443]  with (m+n+p)q=113.

[0444]  and having the following specific viscosities:

[0445] Test N^(o) 36:

[0446] The polymer used in this test, at 0.8% by dry weight with respect to the dry weight of marble, has a specific viscosity of 1.19 and illustrates the invention.

[0447] Test N^(o) 37:

[0448] The polymer used in this test, at 0.8% by dry weight with respect to the dry weight of marble, has a specific viscosity of 1.31 and illustrates the invention.

[0449] Test N^(o) 38:

[0450] The polymer used in this test, at 0.8% by dry weight with respect to the dry weight of marble, has a specific viscosity of 1.83 and illustrates the invention.

[0451] Test N^(o) 39:

[0452] The polymer used in this test, at 0.8% by dry weight with respect to the dry weight of marble, has a specific viscosity of 2.04 and illustrates the invention.

[0453] For tests 40 and 41, these are copolymers fully neutralised with soda and consisting of

[0454] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0455] b) 83.0% by weight of a monomer of formula (I) in which:

[0456] R₁ represents hydrogen

[0457] R₂ represents hydrogen

[0458] R represents the methacrylate group

[0459] R′ represents the methyl radical

[0460]  with (m+n+p)_(q 45).

[0461]  and having the following specific viscosities:

[0462] Test N^(o) 40:

[0463] The polymer used in this test, at 0.4% by dry weight with respect to the dry weight of marble, has a specific viscosity of 0.98 and illustrates the invention.

[0464] Test N^(o) 41:

[0465] The polymer used in this test, at 0.4% by dry weight with respect to the dry weight of marble, has a specific viscosity of 2.33 and illustrates the invention.

[0466] All the Brookfield™ viscosity and Zeta potential experimental results measured with the same equipment and under the same operating conditions as in Example 1 are set out in Tables 4a and 4b below. TABLE 4a BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST SPECIFIC 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS VISCOSITY rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 30 3.2% MMA 0.97  750  330 3000  500  700  240 −12.6 13.5% EGMP 83.3% methoxy PEGM 2000 Invention 31 3.2% MMA 1.57 7400  920 13000  1300 8400 1120 −15.7 13.5% EGMP 83.3% methoxy PEGM 2000 Invention 32 3.2% MMA 1.75 19000  2900 22000  3200 20000  3000 −16.8 13.5% EGMP 83.3% methoxy PEGM 2000 Invention 33 3.2% MMA 3.72 20000  2800 25000  3000 22000  2900 −16 13.5% EGMP 83.3% methoxy PEGM 2000 Invention 34 3.2% MMA 3.74 9000 1450 13000  1950 10000  1550 −15.7 13.5% EGMP 83.3% methoxy PEGM 2000 Invention 35 3.2% MMA 5.08 13000  2600 15000  2750 14000  2700 −18.6 13.5% EGMP 83.3% methoxy PEGM 2000

[0467] TABLE 4b BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST SPECIFIC 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS VISCOSITY rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 36 8.0% AA 1.19 2200 780 5000 1700 3200 1140  −6.2 5.5% EGMP 82.0% methoxy PEG MU 5000 4.5% EA Invention 37 8.0% AA 1.31  950 430 4500  700  700 390 −5.7 5.5% EGMP 82.0% methoxy PEG MU 5000 4.5% EA Invention 38 8.0% AA 1.83 6400 970 7000 1100 1900 600 −8.6 5.5% EGMP 82.0% methoxy PEG MU 5000 4.5% EA Invention 39 8.0% AA 2.04 6800 1280  9000 1350 2200 920 −5.6 5.5% EGMP 82.0% methoxy PEG MU 5000 4.5% EA Invention 40 3.5% MMA 0.98 2000 480 1800  660 1890 540 −20.8 13.5% AA 83.0% methoxy PEGM 2000 Invention 41 3.5% MMA 2.33 6400 920 5000 1010 6900 1400  −15.2 13.5% AA 83.0% methoxy PEGM 2000

[0468] A reading of Tables 4a and 4b shows that the use of a copolymer according to the invention having a specific viscosity of no more than 10, preferentially no more than 5 and highly preferentially no more than 2, results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a high mineral material content, stable over time and having a low Zeta potential.

EXAMPLE 5

[0469] The purpose of this example is to illustrate different types and degrees of neutralisation of the dispersing agent according to the invention.

[0470] For this purpose, with the same operating mode and the same equipment as in example 1, tests were carried out, at 0.4% by dry weight with respect to the dry weight of marble, on the following different copolymers, which had different neutralisations for the same composition by weight of monomer and the same specific viscosity.

[0471] These were all copolymers with a specific viscosity of 1.05 and consisting of:

[0472] a) 3.5% by weight methacrylic acid and 13.5% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0473] b) 83.0% by weight of a monomer of formula (I) in which:

[0474] R₁ represents hydrogen

[0475] R₂ represents hydrogen

[0476] R represents the methacrylate group

[0477] R′ represents the methyl radical

[0478]  with (m+n+p)q=45.

[0479] The different types and degrees of neutralisation are as follows:

[0480] Test N^(o) 42:

[0481] The polymer used in this test is fully neutralised with potash and illustrates the invention.

[0482] Test N^(o) 43:

[0483] The polymer used in this test is fully neutralised with ammonium hydroxide and illustrates the invention.

[0484] Test N^(o) 44:

[0485] The polymer used in this test is totally acidic and illustrates the invention.

[0486] Test N^(o) 45:

[0487] The polymer used in this test is fully neutralised with triethanolamine and illustrates the invention.

[0488] Test N^(o) 46:

[0489] The polymer used in this test is fully neutralised with lithium hydroxide and illustrates the invention.

[0490] Test N^(o) 47:

[0491] The polymer used in this test is neutralised to the extent of 50% molar with magnesium hydroxide and illustrates the invention.

[0492] Test N^(o) 48:

[0493] The polymer used in this test is fully neutralised with a mixture composed of 70% molar soda and 30% molar lime and illustrates the invention.

[0494] Test No 49:

[0495] The polymer used in this test is fully neutralised with a mixture composed of 50% molar soda and 50% molar magnesium hydroxide and illustrates the invention.

[0496] All the Brookfield™ viscosity and Zeta potential experimental results measured with the same equipment and under the same operating conditions as in Example 1 are set out in Tables 5a and 5b below. TABLE 5a BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST NEUTRALI- 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS SATION rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 42 3.5% MMA 100 K 1100 255 3000  700 1200 290 −19.5 13.5% AA 83.0% methoxy PEGM 2000 Invention 43 3.5% MMA 100 NH₄OH 6000 840 6000 1100 4500 790 −14.7 13.5% AA 83.0% methoxy PEGM 2000 Invention 44 3.5% MMA 0 2200 490 5000 1000 2500 290 −10.1 13.5% AA 83.0% methoxy PEGM 2000 Invention 45 3.5% MMA 100 TEA 4500 700 4000  900 2900 550 −14.8 13.5% AA 83.0% methoxy PEGM 2000 Invention 46 3.5% MMA 100 Li 4100 670 8000 1050 7000 950 −20.3 13.5% AA 83.0% methoxy PEGM 2000 Invention 47 3.5% MMA 50 Mg 1500 360 3500  650 1700 325 −8.8 13.5% AA 83.0% methoxy PEGM 2000

[0497] TABLE 5b BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST NEUTRALI- 10 100 10 100 10 100 POTENTIAL N° CONSTITUENT MONOMERS SATION rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 48 3.5% MMA 70 Na-30 Ca  4000 620 5000 1000 4000 720 −18.9 13.5% AA 83.0% methoxy PEGM 2000 Invention 49 3.5% MMA 50 Na-50 Mg 4600 800 7000 1100 5200 850 −15.5 13.5% AA 83.0% methoxy PEGM 2000

[0498] A reading of Tables 5a and 5b shows that the use of a copolymer according to the invention, totally acid or partially or totally neutralised with one or more neutralisation agents having a monovalent neutralising function or a polyvalent neutralising function results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a high mineral matter content, stable over time and having a low Zeta potential.

EXAMPLE 6

[0499] This example relates to the grinding of a suspension of natural calcium carbonate in order to refine into a microparticular suspension.

[0500] For this purpose, for each test, 0.75% by dry weight, with respect to the total dry weight of the calcium carbonate, of grinding aid agent to be tested, was introduced into an aqueous suspension of 42% dry matter of a marble coming from the Carrara deposits and with a mean diameter of around 10 μm.

[0501] The suspension circulated in a grinder of the Dyno-Mill type with a fixed cylinder and rotating impeller, whose grinding substance consisted of corundum balls with a diameter in the range from 0.6 millimetres to 1 millimetre.

[0502] The total volume occupied by the grinding substance was 1150 cubic centimetres whilst its weight was 2900 g.

[0503] The grinding chamber had a volume of 1400 cubic centimetres.

[0504] The circumferential speed of the grinder was 10 metres per second.

[0505] The suspension of calcium carbonate was recycled at the rate of 18 litres per hour.

[0506] The outlet of the Dyno-Mill was provided with a separator with 200 micron mesh for separating the suspension resulting from the grinding and the grinding substance.

[0507] The temperature during each grinding test was kept at approximately 60° C.

[0508] At the end of the grinding (T₀), a sample of the pigmentary solution was recovered in a flask. The granulometry of the suspension (% of particles less than 1 micrometre) was measured by means of a Sedigraph™ 5100 granulometer from Micromeritics.

[0509] The Brookfield™ viscosity of the suspension was measured by means of a Brookfield™ type RVT viscometer, at a temperature of 20° C. and speeds of rotation of 10 revolutions per minute and 100 revolutions per minute with the appropriate spindle.

[0510] After leaving at rest for 8 days in the flask, the Brookfield™ viscosity of the suspension was measured by introducing, into the unstirred flask, the appropriate spindle of the Brookfield™ type RVT viscometer, at a temperature of 20° C. and speeds of rotation of 10 revolutions per minute and 100 revolutions per minute (viscosity BS=before stirring).

[0511] The same Brookfield™ viscosity measurements were also carried out once the flask was stirred and constituted the AS (after stirring) viscosity results.

[0512] Thus, in the different tests the following different grinding aid agents were tested.

[0513] Test N^(o) 50:

[0514] This test, illustrating the invention, uses a polymer 100% neutralised with soda, with a specific viscosity of 0.98 and consisting of:

[0515] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0516] b) 83.0% by weight of a monomer of formula (I) in which

[0517] R₁ represents hydrogen

[0518] R₂ represents hydrogen

[0519] R represents the methacrylate group

[0520] R′ represents the methyl radical

[0521]  with (m+n+p)q=45.

[0522] Test N^(o) 51:

[0523] This test, illustrating the invention, uses a polymer fully neutralised with potash, with a specific viscosity of 0.98 and consisting of:

[0524] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0525] b) 83.0% by weight of a monomer of formula (I) in which

[0526] R₁ represents hydrogen

[0527] R₂ represents hydrogen

[0528] R represents the methacrylate group

[0529] R′ represents the methyl radical

[0530]  with (m+n+p)q=45.

[0531] Test N^(o) 52:

[0532] This test, illustrating the invention, uses a polymer, with a specific viscosity of 0.98, fully neutralised so that 50% of the acid groups are neutralised with soda and 50% of the acid groups are neutralised with magnesium hydroxide, and consisting of:

[0533] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0534] b) 83.0% by weight of a monomer of formula (I) in which

[0535] R₁ represents hydrogen

[0536] R₂ represents hydrogen

[0537] R represents the methacrylate group

[0538] R′ represents the methyl radical

[0539]  with (m+n+p)q=45.

[0540] Test N^(o) 53:

[0541] This test, illustrating the invention, uses a non-neutralised polymer, with a specific viscosity of 0.98 and consisting of:

[0542] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0543] b) 83.0% by weight of a monomer of formula (I) in which

[0544] R₁ represents hydrogen

[0545] R₂ represents hydrogen

[0546] R represents the methacrylate group

[0547] R′ represents the methyl radical

[0548]  with (m+n+p)q=45.

[0549] All the Brookfield™ viscosity and Zeta potential experimental results measured with the same equipment and under the same operating conditions as in Example 1 are set out in Table 6 below. TABLE 6 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER DEGREE OF GRANU- INITIAL STIRRING STIRRING ZETA TEST CONSTITUENT NEUTRALISA- LOMETRY 10 100 10 100 10 100 POTENTIAL N° MONOMERS TION/ION (% <1 μm) rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 50 3.4% MMA 100 Na 70.4 2400 370 1700 455 750 170 −15.7 13.6% AA 83.0% methoxy PEGM 2000 Invention 51 3.4% MMA 100 K 73.9 2550 430 1500 535 950 230 −13.4 13.6% AA 83.0% methoxy PEGM 2000 Invention 52 3.4% MMA 50 Na-50 Mg 72.3 1300 300  650 120 650 112 −11.9 13.6% AA 83.0% methoxy PEGM 2000 Invention 53 3.4% MMA 0 70.7 2850 460 1350 315 500  93 −8.7 13.6% AA 83.0% methoxy PEGM 2000

[0550] A reading of Table 6 shows that the use of a copolymer according to the invention, totally acidic or partially or totally neutralised with one or more neutralisation agents having a monovalent neutralisation function or a polyvalent neutralisation function results in the obtaining of aqueous solutions of ground mineral pigments and/or fillers, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential.

EXAMPLE 7

[0551] This example relates to the grinding of a suspension of dolomite in order to refine it into a microparticular suspension.

[0552] For this purpose, for each test, a grinding aid agent to be tested was introduced, to the extent of 0.5% by dry weight, with respect to the total dry weight of dolomite, into an aqueous suspension with 65% dry matter of a dolomite whose 4.2% are not passing through a 100 μm sieve and whose median diameter measured by means of a CILAS type 850 granulometer was 15.03 micrometres.

[0553] The suspension circulated in a grinder of the Dyno-Mill type with fixed cylinder and rotating impeller, whose grinding substance consisted of balls of corundum with a diameter in the range 0.6 millimetres to 1 millimetre.

[0554] The total volume occupied by the grinding substance was 1150 cubic centimetres whilst its weight was 2900 g.

[0555] The grinding chamber had a volume of 1400 cubic centimetres.

[0556] The circumferential speed of the grinder was 10 metres per second.

[0557] The suspension of dolomite was recycled at 18 litres per hour.

[0558] The outlet from the Dyno-Mill was provided with a separator with meshes of 200 microns for separating the suspension resulting from the grinding, and the grinding substance.

[0559] The temperature during each grinding test was maintained at approximately 60° C.

[0560] At the end of grinding (T₀), a sample of the pigmentary suspension was recovered in a flask. The granulometry of the suspension (% of particles less than 2 micrometres) was measured by means of a CILAS type 850 granulometer.

[0561] The Brookfield™ viscosity of the suspension was measured by means of a Brookfield™ type RVT viscometer, at a temperature of 20° C. and speeds of rotation of 10 revolutions per minute and 100 revolutions per minute with the appropriate spindle.

[0562] After a residence time of 8 days in the flask, the Brookfield™ viscosity of the suspension was measured by introducing, into the unstirred flask, the appropriate spindle of the Brookfield™ type RVT viscometer, at a temperature of 20° C. and speeds of rotation of 10 revolutions per minute and 100 revolutions per minute (viscosity BS=before stirring).

[0563] The same Brookfield™ viscosity measurements were also made once the flask had been stirred and constitute the AS (after stirring) viscosity results.

[0564] Thus, in the different tests, the following different grinding aid agents were tested.

[0565] Test N^(o) 54:

[0566] This test, illustrating the invention, uses a non-neutralised polymer, with a specific viscosity of 0.98 and consisting of:

[0567] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0568] b) 83.0% by weight of a monomer of formula (I) in which

[0569] R₁ represents hydrogen

[0570] R₂ represents hydrogen

[0571] R represents the methacrylate group

[0572] R′ represents the methyl radical

[0573]  with (m+n+p)q=45.

[0574] Test N^(o) 55:

[0575] This test, illustrating the invention, uses a polymer fully neutralised with soda, with a specific viscosity of 0.98 and consisting of:

[0576] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0577] b) 83.0% by weight of a monomer of formula (I) in which

[0578] R₁ represents hydrogen

[0579] R₂ represents hydrogen

[0580] R represents the methacrylate group

[0581] R′ represents the methyl radical

[0582]  with (m+n+p)q=45.

[0583] Test N^(o) 56:

[0584] This test, illustrating the invention, uses a polymer fully neutralised with potash, with a specific viscosity of 0.98 and consisting of:

[0585] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0586] b) 83.0% by weight of a monomer of formula (I) in which

[0587] R₁ represents hydrogen

[0588] R₂ represents hydrogen

[0589] R represents the methacrylate group

[0590] R′ represents the methyl radical

[0591]  with (m+n+p)q=45.

[0592] All the Brookfield™ viscosity and Zeta potential experimental results measured with the same equipment and under the same operating conditions as in Example 1 are set out in Table 7 below. TABLE 7 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER DEGREE OF GRANU- INITIAL STIRRING STIRRING ZETA TEST CONSTITUENT NEUTRALISA- LOMETRY 10 100 10 100 10 100 POTENTIAL N° MONOMERS TION/ION (% <2 μm) rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 54 3.4% MMA 0 50.4 1070 183 1940 274 1330 205 −5.7 13.6% AA 83.0% methoxy PEGM 2000 Invention 55 3.4% MMA 100 Na 56.6 2070 266 2300 305 1910 261 −7.0 13.6% AA 83.0% methoxy PEGM 2000 Invention 56 3.4% MMA 100 K 52.1 2570 341 3470 436 3460 439 −8.2 13.6% AA 83.0% methoxy PEGM 2000

[0593] A reading of Table 7 shows that the use of a copolymer according to the invention results in the obtaining of aqueous suspensions of ground dolomites, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential.

EXAMPLE 8

[0594] This example relates to the grinding of a suspension of natural calcium carbonate in order to refine it into a microparticular suspension in an industrial microelement grinder, followed by a reconcentration and a dispersal of the concentrated suspension by means of the dispersing agent according to the invention.

[0595] For this purpose, for each test according to the invention (Tests 57 and 58), after a grinding of an aqueous suspension with 41% dry matter of a Norwegian marble, using 0.6% by dry weight, with respect to the total dry weight of the calcium carbonate, of a grinding aid agent according to the invention, a polymer neutralised to the extent of 50% molar by potash, with a specific viscosity equal to 0.98 and consisting of:

[0596] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0597] b) 83.0% by weight of a monomer of formula (I) in which

[0598] R₁ represents hydrogen

[0599] R₂ represents hydrogen

[0600] R represents the methacrylate group

[0601] R′ represents the methyl radical

[0602]  with (m+n+p)q=45,

[0603]  a thermal reconcentration of the refined suspension obtained was carried out until a slurry was obtained with a dry calcium carbonate concentration of 72%.

[0604] For Test N^(o) 57 illustrating the invention, there was introduced into the thermal concentrator, during the reconcentration step, 0.75% by dry weight, with respect to the dry weight of calcium carbonate, of the copolymer fully neutralised with soda, with a specific viscosity of 0.98 and consisting of:

[0605] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0606] b) 83.0% by weight of a monomer of formula (I) in which

[0607] R₁ represents hydrogen

[0608] R₂ represents hydrogen

[0609] R represents the methacrylate group

[0610] R′ represents the methyl radical

[0611]  with (m+n+p)q=45.

[0612] For Test N^(o) 58 illustrating the invention, there was introduced into the thermal concentrator, during the reconcentration step, 0.75% by dry weight, with respect to the dry weight of calcium carbonate, of the copolymer with a specific viscosity of 0.98, fully neutralised with potash and consisting of:

[0613] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0614] b) 83.0% by weight of a monomer of formula (I) in which

[0615] R₁ represents hydrogen

[0616] R₂ represents hydrogen

[0617] R represents the methacrylate group

[0618] R′ represents the methyl radical

[0619]  with (m+n+p)q=45.

[0620] All the Brookfield™ viscosity, Zeta potential and granulometry experimental results measured with the same equipment and under the same operating conditions as in Example 1 are set out in Table 8 below. TABLE 8 DISPERSANT USED IN BROOKFIELD ™ VISCOSITY (mPa · s) RECONCENTRATION 8 days BEFORE 8 days AFTER DEGREE OF GRANU- INITIAL STIRRING STIRRING ZETA TEST CONSTITUENT NEUTRALISA- LOMETRY 10 100 10 100 10 100 POTENTIAL N° MONOMERS TION/ION (% <1 μm) rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 57 3.4% MMA 100 Na 76.6 2520 942 1100 900 1650 565 −7.2 13.6% AA 83.0% methoxy PEGM 2000 Invention 58 3.4% MMA 100 K 75.7 1750 583 1200 690 1320 407 −7.8 13.6% AA 83.0% methoxy PEGM 200

[0621] A reading of Table 8 shows that the use of a copolymer according to the invention results in the obtaining of aqueous suspensions of mineral pigments and/or fillers ground and then reconcentrated, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential.

EXAMPLE 9

[0622] This example relates to the preparation of a suspension of different mineral fillers by simple dispersion and the revealing of the properties afforded by the presence of at least one monomer of formula (I) in the non-ionic monomer.

[0623] For this purpose, the aqueous suspension of mineral filler to be tested is prepared by the introduction first of all of the agent to be tested into the water and then of the mineral material to be dispersed.

[0624] Test N^(o) 59:

[0625] This test illustrates the invention and uses kaolin (kaolin SPS from ECC) as a mineral material at a dry matter concentration of 60.5% and, as a dispersing agent, 1.0% by dry weight, with respect to the dry weight of kaolin, of a copolymer with a specific viscosity of 0.98, fully neutralised with potash and consisting of:

[0626] a) 3.4% by weight methacrylic acid and 13.6% by weight acrylic acid as anionic monomers with a monocarboxylic function

[0627] b) 83.0% by weight of a monomer of formula (I) in which

[0628] R₁ represents hydrogen

[0629] R₂ represents hydrogen

[0630] R represents the methacrylate group

[0631] R′ represents the methyl radical

[0632]  with (m+n+p)q=45.

[0633] Test N^(o) 60:

[0634] This test illustrates the invention and uses, as a mineral material, titanium dioxide sold by Tioxide under the name R-HD2 at a dry matter concentration of 60.4% and, as a dispersing agent, 0.4% in dry weight, with respect to the dry weight of titanium dioxide, of the same copolymer as the one used in Test N^(o) 59.

[0635] Test N^(o) 61:

[0636] This test illustrates the invention and uses, as a mineral material, lime supplied by Aldrich at a dry matter concentration of 60.6% and, as a dispersing agent, 1.0% by dry weight, with respect to the dry weight of lime, of the same copolymer as the one used in Test N^(o) 59.

[0637] Test N^(o) 62:

[0638] This test illustrates the invention and uses, as a mineral material, magnesium hydroxide supplied by Aldrich at a dry matter concentration of 60.5% and, as a dispersing agent, 0.4% by dry weight, with respect to the dry weight of magnesium hydroxide, of the same copolymer as the one used in Test N^(o) 59.

[0639] Test N^(o) 63:

[0640] This test illustrates the invention and uses, as a mineral material, a chalk sold by Omya under the name Etiquette Violette at a dry matter concentration of 70% and, as a dispersing agent, 0.3% by dry weight, with respect to the dry weight of chalk, of the same copolymer as the one used in Test N^(o) 59.

[0641] All the Brookfield™ viscosity and Zeta potential experimental results measured with the same equipment and under the same operating conditions as in Example 1 are set out in Table 9 below. TABLE 9 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING ZETA TEST DRY 10 100 10 100 10 100 POTENTIAL N° MINERAL FILLER MATTER % rev/min rev/min rev/min rev/min rev/min rev/min (mV) Invention 59 Kaolin 60.5 3830  760 8000 1400 5200 950 −10.6 Invention 60 Titanium dioxide 60.4 2600  480 3000  550 1100 170 −17.2 Invention 61 Chalk 60.6 800 530 20000  4800 10000  4400  −7.6 Invention 62 Magnesium 60.5 400 180 3000 3800  200 130 −3.6 hydroxide Invention 63 Chalk 70 790 146 3880  891 1740 277 −28

[0642] A reading of Table 9 shows that the use of a copolymer according to the invention containing, as a non-ionic monomer, at least one monomer of formula (I) results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate to high mineral material content, stable over time and having a low Zeta potential, whatever the mineral material used.

EXAMPLE 10

[0643] The purpose of this example is to illustrate the low sensitivity of the aqueous suspensions according to the invention to alkaline pHs.

[0644] To do this, a quantity of polymer to be tested corresponding to 0.73% by dry weight with respect to the dry weight of mineral material was introduced into water.

[0645] After homogenisation of the polymer in the water by stirring, the pH of the medium was adjusted to 9 by adding soda.

[0646] The pH being constant, the necessary quantity of mineral material for obtaining a dry matter concentration of 70% was then introduced.

[0647] After 30 minutes stirring, ammonium hydroxide was added until a pH of 10 was obtained.

[0648] The sample was then divided into three parts.

[0649] The first part was reserved for a study of the Brookfield™ viscosity carried out with the same operating method and the same equipment as in the previous examples.

[0650] The second part of the sample was stirred for 30 minutes. After these 30 minutes of stirring, the pH was lowered to 7.5 by means of acetic acid.

[0651] At the end of 20 minutes additional stirring, a measurement of conductivity of the aqueous suspension of mineral material was carried out by means of a conductivity meter type LF 320 sold by Wissenschaftliche Technische Werkstätten. This value then corresponded to the conductivity of the suspension at a pH of 7.5. The sample was then subjected to a study of Brookfield™ viscosity as previously described.

[0652] The third part of the sample was stirred for 30 minutes. After these 30 minutes of stirring, the pH was raised to 13 by adding soda.

[0653] At the end of 20 minutes additional stirring, a measurement of conductivity of the aqueous suspension of mineral material was carried out using the same conductivity meter as the one used previously. This value then corresponded to the conductivity of the suspension at a pH of 13. The sample was then subjected to a study of Brookfield™ viscosity as previously described.

[0654] Test N^(o) 64:

[0655] This test illustrates the prior art and uses, as a mineral material, a precipitated calcium carbonate sold by Solvay under the name Socal™ P3 and, as a dispersing agent, a polyacrylic acid with a specific viscosity of 0.84.

[0656] Test N^(o) 65:

[0657] This test illustrates the invention and uses, as a mineral material, a precipitated calcium carbonate sold by Solvay under the name Socal™ P3 and, as a dispersing agent, the same copolymer as the one used in Test N^(o) 59.

[0658] All the Brookfield™ viscosity and conductivity experimental results are set out in Table 10 below. TABLE 10 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING TEST 10 100 10 100 10 100 N° pH CONDUCTIVITY mS/cm rev/min rev/min rev/min rev/min rev/min rev/min Prior art 64 7.5 2.27 10000  2764 Viscosity too not measurable 10 2.7 3460  926 3480 high 3390 858 13 11.2 50800  7440 Viscosity 994 not measurable too high Invention 65 7.5 1.4  320  252 1020 442  430 300 10 1.7  400  362  820 531  450 366 13 4.8 8920 2500 10500  4230  8600 3204 

[0659] A reading of Table 10 shows that the use of a copolymer according to the invention containing at least one monomer of formula (I) as a non-ionic monomer results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate or high mineral matter content, stable over time and having a low sensitivity to alkaline pHs.

EXAMPLE 11

[0660] The purpose of this example is to illustrate the low sensitivity of the aqueous suspensions according to the invention to acidic or weakly alkaline pHs.

[0661] To do this, a quantity of polymer to be tested corresponding to 0.45% by dry weight with respect to the dry weight of mineral material was introduced into water.

[0662] After homogenisation of the polymer in water by stirring, the necessary quantity of mineral material for obtaining a dry matter concentration of 60% was introduced.

[0663] After 30 minutes stirring, the sample was then divided into three parts for measurements of Brookfield™ viscosity and conductivity on each of the parts of the sample with the same operating method and the same equipment as used in the previous example.

[0664] The first part corresponded to a natural pH of a dispersion of 8 and was reserved for the study of Brookfield™ viscosity as described in Example 10.

[0665] For the second part of the sample, the pH was reduced to 6 by means of hydrochloric acid.

[0666] At the end of 20 minutes additional stirring, a measurement of conductivity of the aqueous suspension of the mineral matter was carried out. This value then corresponded to the conductivity of the suspension for a pH of 6.0. The sample was then subjected to a study of Brookfield™ viscosity as previously described.

[0667] For the third part of the sample, the pH was reduced to 3 by a further addition of hydrochloric acid.

[0668] At the end of 20 minutes additional stirring, a measurement of conductivity of the aqueous suspension of mineral matter was carried out using the same conductivity meter as the one used previously. This value then corresponded to the conductivity of the suspension at a pH of 3. This sample was then subjected to a study of Brookfield™ viscosity as previously described.

[0669] Test N^(o) 66:

[0670] This test illustrates the prior art and uses, as a mineral material, a titanium dioxide sold by Tioxide under the name R-HD2 and, as a dispersing agent, a copolymer sold by Coatex under the name Coatex BR3, with a specific viscosity of 1.3.

[0671] In this test, it was impossible to continue the dispersion when the pH had dropped to 3 since the titanium oxide had caked and blocked the disperser.

[0672] The measurements of Brookfield™ viscosity and conductivity could therefore not be carried out at this pH value.

[0673] Test N^(o) 67:

[0674] This test illustrates the invention and uses, as a mineral matter, a titanium dioxide sold by Tioxide under the name R-HD2 and, as a dispersing agent, the same copolymer as that used in Test N^(o) 59.

[0675] All the Brookfield™ viscosity and conductivity experimental results are set out in Table 11 below. TABLE 11 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING TEST FINAL DRY CONDUCTIVITY 10 100 10 100 10 100 N° pH EXTRACT (%) Ms/cm rev/min rev/min rev/min rev/min rev/min rev/min Prior art 66 3 Dispersion Dispersion Dispersion Dispersion Dispersion Dispersion Dispersion Dispersion BR 3 impossible impossible impossible impossible impossible impossible impossible impossible 6 59.5 2 24040  2592  Viscosity too high not measur- able 8 59.1 1.9  214 160 302 218 165  98 Invention 67 3 59.9 4.84  79 136  95 148  89 102 6 58.9 1.25 3120 374 3400  336 3240  436 8 59.3 0.88  760 138 860 138 660 104

[0676] A reading of Table 11 shows that the use of a copolymer according to the invention containing, as a non-ionic monomer, at least one monomer of formula (I) results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate to high mineral matter content, stable over time and having a low sensitivity to changes from the natural pH of the dispersion to acid to highly acid pHs.

EXAMPLE 12

[0677] The purpose of this example is to illustrate the low sensitivity to ionic strength of the aqueous suspensions according to the invention.

[0678] To do this, with the same operating method and with the same equipment as before, the mineral materials are put in suspension at a dry matter concentration of 72% in salt water with a sodium chloride content of 2 moles per litre of bipermuted water.

[0679] Test N^(o) 68:

[0680] This test illustrates the prior art and uses, as a mineral material, a precipitated calcium carbonate sold by Solvay under the name Socal™ P3 and, as a dispersing agent, 0.73% by dry weight, with respect to the dry weight of precipitated calcium carbonate, a polyacrylic acid with a specific viscosity of 0.84.

[0681] It was impossible to put all the precipitated calcium carbonate in suspension, the spindle of the stirrer being locked before the end of the introduction of the total quantity of precipitated calcium carbonate.

[0682] Test N^(o) 69:

[0683] This test illustrates the invention and uses, as a mineral material, a precipitated calcium carbonate (sold by Solvay under the name Socal™ P3) and, as a dispersing agent, 0.73% by dry weight, with respect to the dry weight of precipitated calcium carbonate, the same copolymer as the one used in Test N^(o) 53.

[0684] It was possible to put all the precipitated calcium carbonate in suspension and the Brookfield™ viscosity and conductivity experimental results are set out in Table 12 below. TABLE 12 BROOKFIELD ™ VISCOSITY (mPa · s) 8 days BEFORE 8 days AFTER INITIAL STIRRING STIRRING TEST CONDUCTIVITY 10 100 10 100 10 100 N° pH mS/cm rev/min rev/min rev/min rev/min rev/min rev/min Prior 68 9 Impossible to put all the calcium carbonate in suspension art Invention 69 9 43.8 590 446 1000 960 620 544

[0685] A reading of Table 12 shows that the use of a copolymer according to the invention containing, as a non-ionic monomer, at least one monomer of formula (I) results in the obtaining of aqueous suspensions of mineral pigments and/or fillers, according to the invention, with a moderate to high mineral matter content, stable over time and having a low sensitivity to the ionic strength of the medium, thus making it possible to obtain aqueous suspensions of mineral pigments and/or fillers which can be used in the field of drilling muds, in particular saturated salt muds and sea water muds.

EXAMPLE 13

[0686] This example relates to the use of the dispersing agent, copolymer according to the invention in the field of paint and more particularly water-based glazed paint. To do that, two tests are carried out.

[0687] Test n^(o) 70, which illustrates the prior art, uses the dispersing agent COATEX BR 3

[0688] Test n^(o) 71, which illustrates the invention, uses the 100% potash neutralised polymer of test n^(o) 42.

[0689] For the test n^(o) 70 illustrating the prior art, the constituents of the said water-based glazed paint were added in succession, these being:

[0690] 40 g of monopropylene glycol

[0691] 64 g of water

[0692] 5 g of dispersing agent COATEX BR 3 at 40% solid content

[0693] 2 g of a biocide, marketed by TROY under the name of MERGAL™ K6N

[0694] 1 g of an anti-foaming agent marketed by HENKEL under the name of NOPCO™ NDW

[0695] 150 g of a calcium carbonate marketed by OMYA under the name of OMYA DP 80 OG

[0696] 200 g of titanium dioxide marketed by MILLENNIUM under the name RHD2

[0697] These constituents are stirred during 20 minutes, and then, the other constituents are added in succession, these being:

[0698] 450 g of a styrene-acrylic binder in dispersion, marketed by RHODIA under the name of RHODOPAS™ DS 910

[0699] 30 g of butyldiglycol

[0700] 100 g of water

[0701] 4 g of a thickening agent marketed by COATEX under the name COATEX BR100P

[0702] 1 g of 28% ammonia and

[0703] 3 g of NOPCO™ NDW

[0704] After agitating the aqueous composition made up in this way for a few minutes at a pH equal to 8.7 and after observing a good slurrying, the Brookfield™ viscosities of the different compositions are measured at 25° C. and at 10 revolutions per minute and 100 revolutions per minute using a standard RVT Brookfield™ viscometer fitted with the requisite spindle. They are equal to 3400 mPa.s at 10 rpm and to 1900 mPa.s at 100 rpm.

[0705] The ICI viscosity, which is a high shear (10 000 s⁻¹) viscosity, is measured with the use of a plan cone viscometer.

[0706] We obtain a ICI viscosity of 1.5.

[0707] The Stormer (KU) viscosity is also measured in Krebs Unit with the use of a Stormer viscometer.

[0708] We obtain a Stormer viscosity of 94 KU.

[0709] Test N^(o) 71:

[0710] For this test illustrating the invention, the constituents of the water-based glazed, paint are added in succession, these being:

[0711] 40 g of monopropylene glycol

[0712] 62.7 g of water

[0713] 6.3 g of the polymer of the test n^(o) 42 at a solid content of 31.6%

[0714] 2 g of a biocide, marketed by TROY under the name of MERGAL™ K6N

[0715] 1 g of an anti-foaming agent marketed by HENKEL under the name of NOPCO™ NDW

[0716] 150 g of a calcium carbonate marketed by OMYA under the name of OMYA DP 80 OG

[0717] 200 g of titanium dioxide marketed by MILLENNIUM under the name RHD2

[0718] These constituents are stirred during 20 minutes and then, the other constituents are added in succession, these being:

[0719] 450 g of a styrene-acrylic binder in dispersion, marketed by RHODIA under the name of RHODOPAS™ DS 910

[0720] 30 g of butyldiglycol

[0721] 100 g of water

[0722] 4 g of a thickening agent marketed by COATEX under the name COATEX BR1002

[0723] 1 g of 28% ammonia and

[0724] 3 g of NOPCO™ NDW

[0725] After agitating the aqueous composition made up in this way for a few minutes at a pH equal to 8.7 and after observing a good slurrying, the Brookfield™ viscosities of the different compositions are measured at 25° C. and at 10 revolutions per minute and 100 revolutions per minute using a standard RVT Brookfield™ viscometer fitted with the requisite spindle. They are equal to 3000 mPa.s at 10 revolutions per minute and 1700 mPa.s at 100 revolutions per minute.

[0726] The ICI viscosity, which is a high shear (10 000 S⁻¹) viscosity, is measured with the use of a plan cone viscometer.

[0727] We obtain a ICI viscosity of 1.4.

[0728] The Stormer (KU) viscosity is also measured in Krebs Unit with the use of a Stormer viscometer.

[0729] We obtain a Stormer viscosity of 93 KU.

[0730] The comparison between the obtained values for the use of the copolymer according to the invention and the obtained values for the use of a polymer, usually used by the skilled man in the art, allows to note that the copolymer according to the invention can be used in the field of paints.

EXAMPLE 14:

[0731] This example concerns the use of the dispersing agent, the copolymer according to the invention, in the field of plastics materials.

[0732] For this purpose, an aqueous suspension of calcium carbonate (marble) obtained after flocculation was filtered in order to end up with a marble filtration cake with a mean diameter of 2 micrometres measured by means of a Sedigraph™ 5100.

[0733] From this cake, the aqueous suspension of marble was prepared by introducing into the cake the required quantity by dry weight of the polymer agent of Test N^(o) 4 according to the invention with respect to the dry weight of the said cake to be put in suspension in order to obtain an aqueous suspension of marble at a dry matter concentration of 68%.

[0734] Once this suspension had been produced, it was dried at a temperature of less than 105° C. by the use of a laboratory dryer of the Niro™ type.

[0735] The powder obtained without any agglomerate was then divided into two samples, one of which was to be the subject of the dispersion test in a thermoplastic resin and the other the subject of the dispersion test in a thermosetting resin.

[0736] Test N^(o) 72:

[0737] This test, illustrating the invention, represents the test on the dispersion of the marble powder, previously obtained, in a thermoplastic resin.

[0738] For this purpose, 300 grams of previously prepared marble in powder form with a mean diameter of 2 μm was introduced into a Z-arm Guittard mixer with a capacity of 1.5 litres and having a vessel electrically heated to 240° C.

[0739] After 15 minutes of preliminary heating of the load at 240° C., 3 grams of commercial available zinc stearate and 125.5 grams of polypropylene homopolymer sold by the company Appryl under the name PPH 3120MN1 were introduced.

[0740] The whole was mixed for 20 minutes at this temperature and at a speed of 42 revolutions/minute.

[0741] With the mixture thus prepared, a calendering of part of this mixture was then carried out in the form of sheets which were cut into small cubes 2 to 3 millimetres square and whose MFI fluidity index was measured at 230° C. under a load of 2.16 kg and 10 kg with a 2.09 mm diameter die.

[0742] The MFI obtained was 8.0 g/10 min (230° C.-2.16 kg-2.09 mm) and 132 g/10 min (230° C.-10 kg-2.09 mm).

[0743] This MFI result shows that the use of the agent, the copolymer according to the invention, results in loaded thermoplastic compositions which can be used in the field of thermoplastics.

[0744] Test N^(o) 73:

[0745] This test, illustrating the invention, represents the test for the dispersion of marble powder, previously obtained, in a thermosetting resin of the unsaturated polyester type.

[0746] For this purpose, in a 500 ml metallic box, 90 grams of unsaturated polyester resin reference Palapreg P18 from BASF, 60 grams of an additive called “Low Profile” and available under the reference LP40A from Union Carbide and 300 grams of the marble powder obtained were weighed.

[0747] After 24 hours of storing at rest, a presence of settling or sedimentation before homogenisation was noted.

[0748] Homogenisation of the mixture by stirring with a spatula was then carried out, and then the Brookfield™ viscosity at 100 revolutions/min was measured after this 24 hours by means of a Brookfield™ type RVT viscometer equipped with the module 7.

[0749] It was 32,000 mPa.s.

[0750] It should be noted that this premixing of the polyester and calcium carbonate can be used for manufacturing preimpregnates of the SMC (Sheet Moulding Compound) or BMC (Bulk Moulding Compound) type.

EXAMPLE 15

[0751] This example concerns the use of an aqueous suspension of mineral fillers according to the invention in the field of paper. It relates more specifically to the determination of the different Brookfield™ viscosity and water retention values of the different 100% calcium carbonate coating colors.

[0752] Test N^(o) 74:

[0753] This test illustrates the prior art and uses a coating color composed of:

[0754] 100 parts, expressed as dry matter, of an aqueous suspension according to the prior art, at 72% by dry weight of calcium carbonate having a particle such as 75% of the particles have a diameter less than 1 μm determined by Sedigraph™ 5100 and having 0-75% by dry weight of a dispersing agent marketed by Coatex under the name M 777,

[0755] 12 parts, expressed as dry matter, of a styrene-butadiene latex sold by Dow under the name “DL 950”,

[0756] 0.5 parts, expressed as dry matter, of a water retention agent marketed by Coatex under the name Rheocoat™ 35.

[0757] The solid content of the coating color is about 65%.

[0758] Test N^(o) 75:

[0759] This test illustrates the invention and uses a coating color composed of:

[0760] 100 parts, expressed as dry matter, of an aqueous suspension according to the invention, at 72% by dry weight of calcium carbonate having a particle such as 75% of the particles have a diameter less than 1 μm determined by Sedigraph™ 5100 and having 0-75% by dry weight of a dispersing agent according to the invention and composed of 20% by weight of acrylic acid; 80% of methoxy PEG 2000 methacrylate having a specific viscosity of 1.26,

[0761] 12 parts, expressed as dry matter, of a styrene-butadiene latex sold by Dow under the name “DL 950”,

[0762] 0.5 parts, expressed as dry matter, of a water retention agent marketed by Coatex under the name Rheocoat™ 35.

[0763] The solid content of the coating color is about 65%.

[0764] The results of the measurements of Brookfield™ viscosity determined at 10 and 100 revolutions per minute at 25° C. by means of a Brookfield™ viscometer type DV-1 equipped with the appropriate spindle are:

[0765] For test n^(o) 74 according to the prior art:

[0766] Brookfield™ viscosity at 10 rpm=8000 mPa.s

[0767] Brookfield™ viscosity at 100 rpm=1500 mPa.s

[0768] For test n^(o) 75 according to the invention.

[0769] Brookfield™ viscosity at 10 rpm=9200 mPa.s

[0770] Brookfield™ viscosity at 100 rpm=1800 mPa.s

[0771] The results of the water retention measurements obtained according to the following method is:

[0772] For test n^(o) 74 according to the prior art, the water volume after 10 minutes is 3.2 ml,

[0773] For test n^(o) 75 according to the invention, the water volume after 10 minutes is 2.8 ml.

[0774] So, in order to measure the water retentions, the paper coating color to be tested is subjected to a pressure of 100 psi (7 bars) in a standard cylinder, equipped with a surface of the filter paper type capable of allowing water to pass.

[0775] After 10 minutes, the volume of water collected is measured in ml.

[0776] The lower the volume of water collected at the end of 10 minutes, the better is the retention.

[0777] To do this, use is made of an “API Fluid Loss Measurement” filter press from Baroid, which is composed essentially of a clamp provided with a clamping screw for locking the three parts of the filter body.

[0778] This body is composed of:

[0779] a base with a hole provided with a nozzle through which the filtrate flows. This base supports a metallic sieve with a mesh of 60 to 80, on which is placed the 90 mm diameter filter paper (Whatman™ N^(o)50), the equivalent of which is the DURIEUX BLEU™ N^(o) 3 type,

[0780] a cylinder with an inside diameter of 76.2 mm and a height of 128 mm,

[0781] a cover provided with a compressed gas inlet, whose seal with the cylinder is provided by means of a flat joint, of the same type as those placed on the base.

[0782] To use the filter press, the following are fitted in the following order:

[0783] the joint on the base

[0784] the sieve on the joints

[0785] the filter paper on the sieve

[0786] the second joint on the filter paper

[0787]  and the cylinder is fitted on the base before locking the bayonet system.

[0788] Then it is filled with the coating color to be tested (approximately 480 g up to 3 cm from the top of the cylinder) before placing the cover on the cylinder, interposing a joint.

[0789] Then the assembly is placed in the clamp and is locked by means of the clamping screw, and then a graduated tube is arranged underneath the nozzle.

[0790] A pressure of 7 bars is applied, simultaneously triggering a chronometer.

[0791] After 20 minutes the volume of fluid collected in the test tube is noted. The accuracy of the result obtained is ±0.2 ml.

[0792] The reading of the previous results shows that the characteristics of the rheology and of the water-retention concerning the test according to the invention allow to use the aqueous suspensions according to the invention in the field of paper and more particularly in the coating of paper. 

1. The use of a slightly anionic and water-soluble copolymer as a dispersing agent and/or an aid to the grinding of mineral pigments and/or fillers in aqueous suspension, characterised in that the said copolymer consists of: a) at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid or diacid hemiesters such as the C₁ to C₄ monoesters of maleic or itaconic acids, or mixtures thereof, b) possibly at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof chosen from amongst monomers with an unsaturated ethylenic chain and a dicarboxylic function such as crotonic, isocrotonic, cinnamic, itaconic, maleic or citraconic acid or carboxylic acid anhydrides, such as maleic anhydride, or chosen from amongst monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methylpropane sulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as vinyl phosphoric acid, ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphonic function such as phosphonic vinyl acid, or mixtures thereof c) at least one non-ionic monomer with an unsaturated ethylenic chain of formula (I):

in which m and p represent a number of alkylene oxide units less than or equal to 150, n represents a number of ethylene oxide units less than or equal to 150, q represents a number at least equal to 1 and such that 5 ≦(m+n+p)q≦150 R₁ is hydrogen or the methyl or ethyl radical R₂ is hydrogen or the methyl or ethyl radical R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides, R′ represents a hydrocarbon radical having 1 to 5 carbon atoms d) possibly a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and e) possibly at least one monomer having at least two unsaturated ethylenic chains and chosen from the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, and the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others, the total of constituents a), b), c), d) and e) being equal to 100% and in that the said copolymer has a specific viscosity of no more than 10, preferably no more than 5 and highly preferentially no more than
 2. 2. The use of a slightly anionic and water-soluble copolymer according to claim 1, characterised in that the said copolymer consists, expressed by weight, of: a) 2% to 85% and even more particularly 2% to 80% of at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid or the hemiesters of diacids such as the C1 to C4 monoesters of maleic or itaconic acids, or mixtures thereof, b) from 0% to 80% and even more particularly from 0% to 50% and very particularly from 0% to 20% of at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof chosen from amongst monomers with an unsaturated ethylenic chain and a dicarboxylic function such as crotonic, isocrotonic, cinnamic, itaconic, maleic or citraconic acid or carboxylic acid anhydrides, such as maleic anhydride, or chosen from amongst monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methyl-propane sulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as vinyl phosphoric acid, ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphonic function such as phosphonic vinyl acid, or mixtures thereof c) from 20% to 95% of at least one monomer with an unsaturated ethylenic chain of formula (I):

in which m and p represent a number of alkylene oxide units less than or equal to 150, n represents a number of ethylene oxide units less than or equal to 150, q represents a number at least equal to 1 and such that 5≦(m+n+p)q≦150 R₁ is hydrogen or the methyl or ethyl radical R₂ is hydrogen or the methyl or ethyl radical R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides, R′ represents a hydrocarbon radical having 1 to 5 carbon atoms d) from 0% to 50% of a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and e) from 0% to 3% of at least one cross-linking monomer chosen from the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, or the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others, the total of constituents a), b), c), d) and e) being equal to 100% and in that the said copolymer has a specific viscosity of no more than 10, preferably no more than 5 and highly preferentially no more than
 2. 3. The use of a slightly anionic and water-soluble copolymer according to claim 2, characterised in that: a) the anionic monomer with unsaturated ethylenic chains and a monocarboxylic function is preferably chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid, b) the anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof is preferably chosen from amongst the monomers with an unsaturated ethylenic chain and a dicarboxylic function such as itaconic or maleic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methyl-propanesulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or mixtures thereof c) the non-ionic monomer with an unsaturated ethylenic chain of formula (I) is such that R₁ represents hydrogen or the methyl or ethyl radical R₂ represents hydrogen or the methyl or ethyl radical R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters as well as unsaturated urethanes such as acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane, allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides, R′ represents a hydrocarbon radical having 1 to 5 carbon atoms d) the monomer of the acrylamide or methacrylamide type or derivatives thereof is chosen from amongst acrylamide or methacrylamide, and the non water-soluble monomer is chosen from amongst ethyl acrylate or styrene e) the cross-linking agent is chosen from amongst the group consisting OL ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, the allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others.
 4. The use of a slightly anionic and water-soluble copolymer according to any one of claims 1 to 3, characterised in that the said copolymer obtained in acid form and possibly distilled can also be partially or completely neutralised by one or more neutralisation agents having a monovalent neutralising function or having a polyvalent neutralising function such as for the monovalent function, those chosen from the group consisting of alkali cations, in particular sodium, potassium, lithium, ammonium or the aliphatic and/or cyclic primary, secondary or tertiary amines such as stearylamine, the ethanolamines (mono-, di-, triethanolamine), mono and diethylamine, cyclohexylamine, methylcyclohexylamine or, for the polyvalent function, those chosen from the group consisting of alkaline-earth divalent cations, in particular magnesium and calcium, or zinc, also consisting of trivalent cations, in particular aluminium, or certain cations with a higher valency.
 5. The use of a slightly anionic and water-soluble copolymer according to claim 4, characterised in that the said copolymer resulting from the copolymerisation reaction can, possibly before or after the complete or partial neutralisation reaction, be treated and separated into several phases, according to static or dynamic methods known to skilled man in the art, by means of one or more polar solvents belonging to the group consisting of water, methanol, ethanol, propanol, isopropanol, the butanols, acetone, tetrahydrofuran or mixtures thereof.
 6. A dispersing agent and/or an agent for assisting the grinding of mineral pigments and/or fillers in aqueous suspension, characterized in that the said agent is a copolymer consisting of: a) at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid or diacid hemiesters such as the C₁ to C₄ monoesters of maleic or itaconic acids, or mixtures thereof, b) possibly at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof chosen from amongst monomers with an unsaturated ethylenic chain and a dicarboxylic function such as crotonic, isocrotonic, cinnamic, itaconic, maleic or citraconic acid or carboxylic acid anhydrides, such as maleic anhydride, or chosen from amongst monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methylpropane sulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as vinyl phosphoric acid, ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphonic function such as phosphonic vinyl acid, or mixtures thereof c) at least one non-ionic monomer with an unsaturated ethylenic chain of formula (I):

in which m and p represent a number of alkylene oxide units less than or equal to 150, n represents a number of ethylene oxide units less than or equal to 150, q represents a number at least equal to 1 and such that 5≦(m+n+p)q≦150 R₁ is hydrogen or the methyl or ethyl radical R₂ is hydrogen or the methyl or ethyl radical R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as acrylurethane, methacrylurethane, dimethylisopropenyl benzylurethane, allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides, R′ represents a hydrocarbon radical having 1 to 5 carbon atoms d) possibly a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and e) possibly at least one cross-linking monomer chosen from the group consisting of ethylene glycol dimethacrylate, trimethylolpropane-triacrylate, allyl acrylate, allyl maleates, methylene-bisacrylamide, methylenebismethacrylamide, tetrallyl-oxyethane, the triallylcyanurates, the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose and others, the total of constituents a), b), c), d) and e) being equal to 100% and in that the said copolymer has a specific viscosity of no more than 10, preferably no more than 5 and highly preferentially no more than
 2. 7. A dispersing agent and/or an agent for assisting the grinding of mineral pigments and/or fillers in aqueous suspension according to claim 6, characterised in that the said agent is a copolymer consisting, expressed by weight, of: a) 2% to 85% and even more particularly 2% to 80% of at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function chosen from amongst the monomers with an unsaturated ethylenic chain and a monocarboxylic function such as acrylic or methacrylic acid or the hemiesters of diacids such as the C₁ to C₄ monoesters of maleic or itaconic acids, or mixtures thereof, b) from 0% to 80% and even more particularly from 0% to 50% and very particularly from 0% to 20% of at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof chosen from amongst monomers with an unsaturated ethylenic chain and a dicarboxylic function such as crotonic, isocrotonic, cinnamic, itaconic, maleic or citraconic acid or carboxylic acid anhydrides, such as maleic anhydride, or chosen from amongst monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methyl-propane sulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as vinyl phosphoric acid, ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and their ethoxylates or chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphonic function such as phosphonic vinyl acid, or mixtures thereof c) from 20% to 95% of at least one monomer with a non-ionic unsaturated ethylenic chain of formula (I):

in which m and p represent a number of alkylene oxide units less than or equal to 150, n represents a number of ethylene oxide units less than or equal to 150, q represents a number at least equal to 1 and such that 5≦(m+n+p)q≦150 R₁ is hydrogen or the methyl or ethyl radical R₂ is hydrogen or the methyl or ethyl radical R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters and unsaturated urethanes such as acrylurethane, methacrylurethane, dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides, R′ represents a hydrocarbon radical having 1 to 5 carbon atoms d) from 0% to 50% of a monomer of the acrylamide or methacrylamide type or derivatives thereof and mixtures thereof or one or more non water-soluble monomers such as alkyl acrylates or methacrylates, vinyl compounds such as vinyl acetate, vinylpyrrolidone, styrene, alphamethylstyrene and derivatives thereof, and e) from 0% to 3% of at least one cross-linking monomer chosen from the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, allyl maleates, methylenebisacrylamide, methylenebis-methacrylamide, tetrallyloxyethane, the triallyl-cyanurates, the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose and others, the total of constituents a), b), c), d) and e) being equal to 100% and in that the said copolymer has a specific viscosity of no more than 10, preferably no more than 5 and highly preferentially no more than
 2. 8. A dispersing agent and/or agent assisting the grinding of mineral pigments and/or fillers in aqueous suspension according to claim 7, characterised in that the said agent is a copolymer consisting of: a) at least one anionic monomer with an unsaturated ethylenic chain and a monocarboxylic function is preferably chosen from amongst the monomers with an unsaturated ethylenic chain and monocarboxylic functions such as acrylic or methacrylic acid, b) possibly at least one anionic monomer with an unsaturated ethylenic chain and a dicarboxylic or sulphonic or phosphoric or phosphonic function or a mixture thereof is preferably chosen from amongst the monomers with an unsaturated ethylenic chain and a dicarboxylic function such as itaconic or maleic acid or preferentially chosen from amongst the monomers with an unsaturated ethylenic chain and a sulphonic function such as acrylamido-methyl-propanesulphonic acid, sodium methallylsulphonate, vinyl sulphonic acid and styrene sulphonic acid or preferentially chosen from amongst the monomers with an unsaturated ethylenic chain and a phosphoric function such as ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate and ethoxylates thereof or mixtures thereof c) at least one non-ionic monomer with an unsaturated ethylenic chain of formula (I) such that R₁ represents hydrogen or the methyl or ethyl radical R₂ represents hydrogen or the methyl or ethyl radical R represents the polymerisable unsaturated radical, belonging to the group of acrylic, methacrylic, maleic, itaconic, crotonic or vinylphthalic esters as well as unsaturated urethanes such as acrylurethane, methacrylurethane, α-α′ dimethylisopropenyl benzylurethane or allylurethane, and to the group of allyl or vinyl ethers or to the group of ethylenically unsaturated amides, R′ represents a hydrocarbon radical having 1 to 5 carbon atoms d) possibly one monomer of the acrylamide or methacrylamide type or derivatives thereof preferentially chosen from amongst acrylamide or methacrylamide, and at least one non water-soluble monomer preferentially chosen from amongst ethyl acrylate or styrene e) possibly at least one cross-linking agent chosen from amongst the group consisting of ethylene glycol dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate, the allyl maleates, methylenebisacrylamide, methylenebismethacrylamide, tetrallyloxyethane, the triallylcyanurates, the allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others.
 9. A dispersing agent and/or an agent assisting the grinding of mineral pigments and/or fillers in aqueous suspension according to any one of claims 6 to 8, characterised in that the said agent is a copolymer neutralised with one or more neutralisation agents having a monovalent neutralising function or having a polyvalent neutralising function such as for the monovalent function, those chosen from the chosen from the group consisting of alkaline cations, in particular sodium, potassium, lithium, ammonium or the aliphatic and/or cyclic primary, secondary or tertiary amines such as stearylamine, the ethanolamines (mono-, di-, triethanolamine), mono and diethylamine, cyclohexylamine, methylcyclohexylamine or, for the polyvalent function, those chosen from the group consisting of alkaline-earth divalent cations, in particular magnesium and calcium, or zinc, also consisting of trivalent cations, in particular aluminium, or certain cations with a higher valency.
 10. A dispersing agent and/or agent for assisting the grinding of mineral pigments and/or fillers in aqueous suspension according to claim 9, characterised in that the said copolymer resulting from the copolymerisation reaction can, possibly before or after the complete or partial neutralisation reaction, be treated and separated into several phases, according to static or dynamic methods known to the skilled man in the art, by means of one or more polar solvents belonging to the group consisting of water, methanol, ethanol, propanol, isopropanol, the butanols, acetone, tetrahydrofuran or mixtures thereof.
 11. An aqueous suspension of fillers and/or pigments characterised in that it contains the agent according to one of claims 6 to 10 and more particularly in that it contains from 0.05% to 5% by dry weight of the said agent with respect to the total dry weight of the fillers and/or pigments, and even more particularly 0.3% to 1.0% by dry weight of the said agent with respect to the total dry weight of the fillers and/or pigments.
 12. An aqueous suspension of fillers and/or pigments according to claim 11, characterised in that the filler and/or pigment is chosen from amongst natural calcium carbonate such as calcite, chalk or marble, synthetic calcium carbonate, also referred to as precipitated calcium carbonate, dolomites, magnesium hydroxide, kaolin, talc, gypsum, titanium dioxide or aluminium hydroxide or any other filler and/or pigment normally used in the papermaking or petroleum field.
 13. An aqueous suspension of fillers and/or pigments according to claim 12, characterised in that it is only slightly sensitive to the pH and ionic strength of the media and in that it has a low Zeta potential, that is to say a. Zeta potential of between 0 and −30 mV and preferentially between 0 and −20 mV.
 14. The use of the aqueous suspension of fillers and/or pigments according to any one of claims 11 to 13 in the papermaking field and more particularly in the manufacture and/or coating of sheets of paper.
 15. Sheets of paper containing the aqueous suspension of fillers and/or pigments according to any one of claims 11 to
 13. 16. The use of the aqueous suspension of fillers and/or pigments according to any one of claims 11 to 13 in the field of drilling muds used for petroleum prospecting or extraction, in particular in the field of saturated salt muds and sea water muds.
 17. A drilling mud containing the aqueous suspension of fillers and/or pigments according to any one of claims 11 to
 13. 18. The use of the dispersing agent and/or of the agent for assisting the grinding of mineral pigments and/or fillers in aqueous suspension according to any one of claims 6 to 10 in the field of paints.
 19. The use of the dispersing agent and/or of the agent for assisting the grinding of mineral pigments and/or fillers in aqueous suspension according to any one of claims 6 to 10 in the field of plastic materials and more particularly in the field of thermoplastic or thermosetting resins. 